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A POPULAR EXPOSITION 



OF 



ELEOTEIOITY 



WITH SKETCHES OF SOME OF ITS 
DISCOVERERS. 



Rev. MARTIN & l BRENNAN, A. M., 

RECTOR OF THE CHURCH OF AT. THOMAS OF AQUIN, ST. LOUIS, MO. 

RECEIVED. * 




NEW YORK: 
D. APPLETON AND COMPANY, 

1, 8, and 6 BOND STREET. 
1885. 






Copyright, 1865, 
By D. APPLETON AND COMPANY. 





RECEIVED, £ 



PREFACE 




The recent extraordinary progress of electricity, 
its stimulus to commerce, and its mysterious pos- 
sibilities, make it, par excellence^ the science of 
sciences of our day. All should be familiar with 
its essential principles at least. 

Many learned and excellent treatises have been 
devoted to the subject, but so illustrated with 
complex and intricate mechanical diagrams as to 
frighten away the timid and uninitiated. 

My sole aim in this little book is simplicity. 
' The mechanical part of the science is continually 
changing; new patents are being daily issued, so 
that a thorough and full description of the mul- 
tiplex machinery, except for a professional, would 
be time wasted. I have, therefore, devoted my 



4 PREFACE. 

care almost entirely to the explanation of princi- 
ples, to the exclusion of mechanics. 

I consider, moreover, that complicated dia- 
grams, by drawing away the mind from the sub- 
ject-matter in hand, confuse rather than simplify. 

I have aimed throughout at manifesting the 
identity of all the forms of electricity, and have 
accordingly so arranged the matter that each suc- 
ceeding form naturally flows from its predecessor. 

I have also given short sketches of the men 
who have added most to the science by their great 
discoveries, and placed the man as closely as pos- 
sible to his work. 

Women should be especially interested in elec- 
tricity. It is woman's science. A woman was the 
discoverer of its dynamic branch. The wife of 
Galvani, the bright daughter of the eminent Gale- 
azzi, is the initial link in the golden chain of illus- 
trious discoverers who have given to us the mod- 
ern science of electro-dymanics. 



CONTENTS. 



CHAPTER PAGE 

I. — Magnetism 7 

II. — The Mariner's Compass 18 

III. — Michael Faraday 26 

IV. — Statical or Common Electricity .... 34 

V. — Atmospheric Electricity 49 

VI. — Benjamin Franklin 63 

VII. — Galvanism, or the Electricity op Chemical 

Action 81 

VIII. — Galvanic Batteries . . . . . .94 

IX — Electro-Chemical Decomposition, Electrotyping, 

and Gilding 104 

X. — Galvani and Volt a 113 

XL — Electro-Magnetism 117 

XII. — Oersted and Ampere 129 

XIII. — The Electric Telegraph 132 

XIV. — Professor Morse 145 

XV. — Magneto-Electricity — Dynamos . . . .152 
XVI. — The Storage of Electricity . . . .158 

XVII.— The Telephone 165 

XVIII. — The Aurora Borealis, or Red Lights op the 

North 175 

APPENDIX.— Table-Moving 183 



By trantf or 

3 




RECEIVED. « > 



&BR&9S 




ELECTRICITY 
AND ITS DISCOVERERS. 



CHAPTER I. 

MAGNETISM. 

Electricity, under the form of magnetism, 
seems to have been both recognized and utilized 
by mankind from all antiquity. There is a dim 
tradition that the magnetic chariot, tehi nan, was 
used in a rude form by the Chinese as far back as 
the reign of the Emperor Hoangti, twenty -six hun- 
dred years before our era. A wagon of this kind, 
to guide the traveler over the great wastes of Asia, 
was certainly in use eleven hundred years before 
Christianity. 

In this apparatus a freely floating needle moved 
the arm and hand of a small figure, which pointed 
toward the south. This wagon was in use in Asia 
down to the fifteenth century. 



8 ELECTRICITY AND ITS DISCOVERERS. 

The magnetic needle was unknown in Europe 
prior to the eleventh or twelfth century. William 
Gilbert, of Colchester, born in 1540, was the first 
to write a regular treatise on magnetism and reduce 
the subject to a scientific basis. According to his 
testimony, Marco Polo was the first European who 
applied the magnetic needle to the purposes of 
navigation. This he did in returning to Europe 
from the East Indies, in the year 1260. According 
to other and more probable testimony, however, 
the magnetic needle was known in European seas 
some seventy years previously. 

Magnetism is derived from Magnesia, a town 
of Lydia, in Asia. An ore of iron, called lodestone, 
has the property of attracting to itself small parti- 
cles of iron, cobalt, and nickel ; and as this ore was 
found in great abundance in Magnesia, it was called 
by Pliny magnes, and hence magnet. 

Lodestone is the magnetic oxide of iron, Fe a 4 , 
and is a union of the protoxide and sesquioxide of 
iron. The scales thrown off under the smith's ham- 
mer are this oxide. 

Lodestone, mounted in a soft-iron frame, consti- 
tuted the original magnet. 

Magnets are natural, artificial, and permanent. 
The magnetic ore of iron is the natural magnet. 






MAGNETISM. 



Steel or hardened iron, when brought into contact 
with a magnet, becomes magnetized, and is called 
an artificial magnet. Soft iron is magnetic only 
when in contact with a magnet, and, when parted 
from the magnet, at once loses the magnetic prop- 
erty. 

Hardened steel, once magnetized, never loses its 
magnetism, and hence is called a permanent mag- 
net. 

When a small magnetic steel bar is freely sus- 
pended on a pivot, it will so arrange itself that one 
end will point toward the north, and the other end, 
by consequence, toward the south ; and, however 
the bar be moved thereafter, it will invariably, the 
disturbing force being withdrawn, restore itself to 
this position, the same end as before pointing north, 
and the same south. This is the most obvious 
property of a magnet, and is called polarity. 

The needle of the compass is simply a magnet- 
ized piece of steel, balanced upon a pivot, and 
placed in a box having a circular card, divided 
into thirty-two equal parts. The end pointing 
north is called the north pole of the magnet, and 
the end pointing south, the south pole. The un- 
like poles of two magnets attract each other, while 
similar poles repel ; that is, a north pole will at- 



10 ELECTRICITY AND ITS DISCOVERERS. 

tract a south pole and repel a north pole, and a 
south pole will repel a south pole and attract a 
north pole. 

"When a piece of soft iron is brought into con- 
tact with a permanent magnet, the soft iron will 
itself become magnetic, and, while in connection 
with the magnet, will attract other smaller pieces 
of metal. This process is called induction, for the 
magnet induces its own magnetic property in the 
soft iron. The soft iron, however, loses its magnet- 
ism immediately on the withdrawal of the magnet. 
A magnet will induce magnetism in soft-iron fil- 
ings in its immediate vicinity, although not in actual 
contact. Magnets, natural or artificial, can induce 
by touch permanent magnetism in a rod of steel 
or hardened iron. 

When one of the poles of a magnet touches 
the end of a soft-iron rod, that portion of the rod 
in contact with the pole will assume the opposite 
magnetism to that of the pole; the positive pole 
inducing negative magnetism, and the negative 
pole positive magnetism. The magnetism of the 
other extremity of the rod will be similar to that 
of the pole. 

If the pole of a magnet touches the center of 
an iron bar, the magnetic fluid of the center will 



MAGNETISM. 11 

be opposite, and that of both ends of the bar will 
be similar to that of the pole. If either pole be 
brought in contact with the center of a circular 
plate of iron, the center will have opposite and the 
rim similar magnetism to that of the pole. 

If a bar-magnet be broken in the center, the 
pieces, instead of having all positive or all negative, 
will each have both positive and negative polarity, 
so that neither can ever be entirely eliminated, or 
parted from the other. 

The generally accepted theory of magnetism is 
that, in any body capable of being magnetized, 
such, for instance, as a bar of iron, there exist two 
fluids, one called the boreal, northern, or positive ; 
and the other the austral, southern, or negative. 
These fluids, in an ordinary piece of soft iron, are 
combined together, and so are in the latent state. 
When the iron becomes magnetized, these fluids are 
set free, one rushing to one and the other to the 
other extremity of the bar. Every atom or mole- 
cule of iron contains both these fluids, and can nev- 
er part with them ; the only change occurring is the 
decomposition of the fluids into their separate ele- 
ments. In a permanent magnet the fluids are dis- 
united in each and every single molecule, the posi- 
tive fluid ranging itself on one side of the molecule 



12 ELECTRICITY AND ITS DISCOVERERS. 

and the negative on the other. The positive of 
each atom throughout the bar neutralizes or dis- 
guises the negative of its neighboring atom, except- 
ing the positive and negative of the atoms at the 
extreme ends. Thus, the fluids of one side of the 
two extreme atoms are free, the positive fluid con- 
stituting the positive pole, and the negative fluid 
the negative pole of the magnet. This explains 
the reason why the central portion of a magnet has 
no magnetic properties, the positive fluid of each 
particle disguising the negative fluid of its neigh- 
bor. Hence, also, a magnet in the form of a ring 
gives no evidence of free magnetism, but, being 
broken, the fragments will be found to be highly 
magnetic. 

The process of induction in soft iron is ex- 
plained in a similar manner. When a rod of soft 
iron is approached toward the negative pole of a 
magnet, the fluids of the atom in immediate prox- 
imity to this pole are separated, the positive being 
forced to the side nearest the magnet, and the nega- 
tive to the other side. This last negative holds the 
positive of the second atom, sending its negative to 
the opposite side, and so on, until the last atom is 
reached, and its positive is disguised by the pre- 
ceding atom's negative and its own negative is set 



MAGNETISM. 13 

free. The magnet being removed, the fluids are 
recombined, and the rod loses its polarity. 

Another theory, more complex, much in vogue, 
however, and very ingenious, is Ampere's. Ac- 
cording to Ampere, currents of electricity are in- 
cessantly running around every particular molecule 
of a magnet. The resultant of these small currents 
produces a great current circling the magnetic bar. 
The difference between a magnet and an ordinary 
rod of iron is, that in the latter the electricity is la- 
tent, and in the former in an active state of motion. 

The harder and more dense the steel, the more 
difficult it is to be magnetized, but the more perma- 
nent the magnet. It would appear that the close- 
ness of the molecules offers a mechanical impedi- 
ment to the free movement of the imponderable 
magnetic fluids. 

Hitherto only iron, cobalt, and nickel have been 
mentioned as sensitive to magnetic influence, but 
Faraday by his experiments discovered many other 
substances susceptible of polarity. Manganese, 
chromium, cerium, titanium, palladium, platinum, 
osmium, and arsenic, with their salts and even 
solutions, are thus susceptible. 

Dr. Faraday by his brilliant researches, besides 
adding greatly to the development of electric sci- 



14 ELECTRICITY AND ITS DISCOVERERS. 

ence in general, did more than any other man to 
demonstrate the identity of magnetism and elec- 
tricity. 

The process by which a piece of steel is con- 
verted into a magnet is technically called a 
" touch" There are many kinds of touches. The 
single touch is the simplest mode of generating 
magnetism in a steel rod. This is accomplished 
by running one pole of a magnet several times over 
the bar to be magnetized, always, however, in the 
same direction. The end of the bar last touched 
by the positive pole of the magnet will become a 
negative pole. 

Magnets are commonly shaped like the letter U, 
and have received the name of horseshoe magnets. 
Several of these magnets are sometimes joined to- 
gether, and thus form a very powerful one, or rather 
a battery of magnets. Magnetism exists entirely 
on the surface, so that a magnetic hollow cyclinder 
will be equally powerful as if it were solid. A 
number of small magnets connected together have 
more power than the same weight of metal in a 
single magnet, because they present more surface. 
Rust, grinding, filing, weaken the power of a mag- 
net, showing magnetism to have more to do with 
the surface than the interior. 



MAGNETISM. 15 

When magnets are ]eft to themselves, they con- 
stantly, though very slowly, lose their magnetism. 
To prevent this loss, a piece of soft iron, called the 
armature, is placed across the poles. The armature, 
becoming magnetic, seems to react upon the mag- 
net, and thus not only to conserve its magnetism, 
but really to increase its intensity. Small weights 
suspended from the armature, and occasionally in- 
creased, will increase the strength of the magnet to 
a certain limit. Thus, a one-pound magnet can be 
made to lift a weight of twenty-eight pounds. 

The attractive force of a magnet is diminished 
by raising its temperature. A magnet heated 
slightly loses a portion of its power, but regains it 
again upon cooling. When heated to redness, it 
loses its polarity completely, and does not recover 
it upon cooling. On the contrary, a decrease of 
temperature increases the magnetic force. 

Coulomb, with a torsion-balance, has found that 
the force of magnetic attraction is inversely as the 
square of the distance, which is the law governing 
the intensities of heat, light, and gravitation. 

A bar of soft iron, when acted upon by a mag- 
net, is equally attracted by both poles, and when 
such a bar is freely suspended over the poles of a 
horseshoe magnet, it will so arrange itself as to be 



16 ELECTRICITY AND ITS DISCOVERERS. 

in the line of the magnetic force — that is, in the 
direction of a line connecting the poles. 

Dr. Faraday found that certain bodies, when 
approached by a magnet, were repelled by both 
poles ; and bars of such substances, when freely sus- 
pended over the poles of a magnet, arranged them- 
selves at right angles to the direction of the mag- 
netic force. All bodies attracted by a magnet, 
however feebly, are called magnetic, and those re- 
pelled diamagnetic. 

The principal diamagnetic substances, in the 
* order of susceptibility, are bismuth, antimony, zinc, 
V' tin, cadmium, mercury, silver, copper. 

Animal flesh has been found to be diamag- 
netic, and a man suspended freely in a horizontal 
position over the poles of a powerful magnet 
would be repelled by both poles, until he pointed 
due east and west, the direction of the poles of 
the magnet being north and south. 

One of the most splendid discoveries of Fara- 
day was that the oxygen of the air is magnetic. 
This property of oxygen must, consequently, be 
an element in the explanation of the origin of 
electric storms and of the aurora borealis. The 
earth itself is considered a great magnet. Gauss 
estimates its magnetic force to be as great as if 



MAGNETISM. 17 

every cubic yard of it contained six one-pound 
magnets. 

According to Ampere the magnetism of the 
earth is occasioned by electric currents constantly 
circling it from east to west in spiral lines. 
These currents are caused -by the sun's rays. 
These spirals induce in the earth a magnetic axis 
at right angles to themselves, and whose poles 
nearly coincide with the earth's geographical poles. 

Both natural and artificial magnets owe their 
polarity to induction from the earth. Tools in 
workshops, placed vertically, become magnetized 
A bar of iron, placed in the magnetic meridian, 
and inclined at an angle corresponding to the dip 
of the needle for the locality, will become mag- 
netic. Sunlight has a magnetic effect on steel; 
and needles, placed in glass bottles of a violet or 
blue color, will become magnets. 

Great advances have been made within a very 
short period in this beautiful science of magnet- 
ism, and yet we have but touched the shores of 
this enchanting wonderland. 



:J 



CHAPTEK II. 

THE MARINER'S COMPASS. 

The present mariner's compass is a delicate 
piece of mechanism. It consists of a long, flat 
lozenge-shaped magnetized needle, balanced hori- 
zontally on a very fine point of some hard sub- 
stance. Everything possible is done to eliminate 
friction. The center of gravity of the needle is 
pierced, and a piece of agate inserted to rest on 
the point of a steel pin. Beneath the needle and 
attached to it, so that they move together, is a 
circular card divided into thirty-two parts, called 
points. The extremities of the needle point to 
two divisions of the card diametrically opposite, 
which are marked IT. and S., and correspond to 
the north and south poles of the needle. The 
extremities of the diameter running across the 
card at right angles to the needle are marked E. 
and W. 

The whole circle of 360° is divided into thirty- 



THE MARINER'S COMPASS. 19 

two points, so that each point consists of 11° 15'. 
Between the N. and the E., for instance, there 
are eight points, marked respectively N. by E., 
K K E., K E. by K, K E., K E. by E., E. 
N. E., E. by K, and E. 

The other quadrants are similarly divided. To 
prevent the compass from being thrown out of a 
horizontal position by the rolling of the ship, it 
is attached to a pair of circular brass hoops or 
gimbals. The outer hoop is firmly fixed to a 
stationary object, and the inner one is attached to 
the outer by two pivots at the extremities of a 
diameter in such a way as to allow it free mo- 
tion within the outer hoop. The compass-box is 
attached to the inner hoop by two other pivots 
at the extremities of a diameter at right angles to 
tfie first diameter. In this way the compass may 
move freely in two directions at right angles to 
one another, and thus its horizontal position is se- 
cured under any and all circumstances. 

In the box containing the compass is a black 
line, called the lubber-line, in the absolute direc- 
tion of a vertical plane cutting the ship from 
stem to stern. The helmsman must keep the di- 
vision of the card which shows his course in con- 
tact with the lubber-line. 



20 ELECTRICITY AND ITS DISCOVERERS. 

The compass first used in the Mediterranean 
was simplicity itself, being merely a piece of lode- 
stone attached to a cork floating in a vessel of 
water. 

It has been found by astronomical observation 
that the needle does not strictly point due north 
and due south, but varies sometimes to the east, 
sometimes to the west, of true geographical north 
and south. The stars are fixed, and never vary 
in their relative positions. The variation or dec- 
lination of the needle for any place or time is 
found by comparing a star's bearing, as indicated 
by the needle, and its bearing, as shown by as- 
tronomical calculation. Columbus was among the 
first to notice the variation of the needle. He 
certainly was the first to perceive that there was 
a line of no variation. There are places upon the 
earth's surface where the direction of the needle 
coincides exactly with the geographic meridian, 
and these places, connected together by an imagi- 
nary and very irregular curve, form the so-called 
lines of no variation. It is generally admitted 
that there are two lines of this character, called 
the east and west line. The course of the west 
line may be traced from the sixtieth parallel of 
latitude to the west of Hudson's Bay, thence in 



THE MARIISTER'S COMPASS. 21 

a southern direction through the American lakes, 
to the West Indies, and the extreme eastern 
point of South America. 

The eastern, beginning in the White Sea, runs 
south in a semicircle until it reaches the seventy- 
first parallel ; it thence runs along the Sea of Ja- 
pan, whence it takes a westward course across 
China and Hindostan to Bombay; it then turns 
east, touches Australia, and goes south. Even these 
lines are not constant, but move from time to time. 

A great deal of care and time have been ex- 
pended by navigators on this matter of the nee- 
dle's variation. Their observations have, in a 
great measure, been systematized, so that they have 
made elaborate charts and tables of the vagaries 
of this priceless but too sensitive guide. In the 
year 1840 General Sabine employed as many as 
fourteen hundred and eighty observations, to ac- 
curately determine the line of no variation in the 
Atlantic Ocean. It may be remarked, however, 
that for the ordinary purposes of navigation the 
needle points toward the north with sufficient accu- 
racy, and the variations may in general be disre- 
garded. When, indeed, there is question of some- 
thing requiring great delicacy and precision, the 
proper corrections must be applied. 



22 ELECTRICITY AND ITS DISCOVERERS. 

The magnetic needle has a small daily and even 
hourly variation. Its north pole declines slightly 
to the west from sunrise to an hour past noon, 
then retrogrades toward the east until eight in 
the evening, and remains stationary during the 
night. It has, moreover, an annual movement, and 
a different movement in winter from that in sum- 
mer. These daily and yearly fluctuations of the 
needle depend, in all probability, upon the differ- 
ences of temperature caused by the apparent course 
of the sun. 

The magnetic needle is also more or less dis- 
turbed by meteoric showers, electric storms, the 
aurora borealis, the lightning's flash, and the vol- 
cano's throe. 

If the magnetic needle be so supported at its 
center of gravity that, instead of being free to 
move in a horizontal plane, it is left free to move 
in a vertical plane, the needle will be found to in- 
cline more or less from a horizontal position ac- 
cording to the location on the earth's surface. 
When north of the equator, the north pole of the 
needle will incline downward; and, when south, 
the south pole will incline or dip. A magnet- 
ized needle of this kind is called a dipping 
needle. It is furnished with a graduated scale, 



THE MARINER'S COMPASS. 23 

circular in form, marking all the degrees of an 
arc, and situated in a vertical plane just beside 
the needle. In the construction of the dipping- 
needle, as in that of the compass - needle, every- 
thing is done to reach the minimum of friction. 
Two tiny steel cylinders are run out from the nee- 
dle on each side of its center of gravity, and these 
rest on knife-edges made of agate. The frame 
supporting the needle is mounted on a tripod hav- 
ing adjusting screws, in order to maintain a per- 
fect level. 

The nearer this needle is brought to the mag- 
netic equator, the nearer its approach to a horizon- 
tal position, and consequently the less the dip or 
inclination. The farther it is moved from the 
magnetic equator in the direction of the magnetic 
pole, the greater the dip. The magnetic equator 
is where the needle assumes a perfectly horizontal 
position, being equally influenced by both poles. 
The magnetic equator does not correspond exactly 
with the geographic equator, but makes with it an 
angle of twelve or thirteen degrees. 

The geographic equator of the earth is a perfect 
curve, or great circle ; but the magnetic equator is 
an irregular double curve, to which the name of 
aclinic line has been given. The magnetic equa- 



24: ELECTKICITY AND ITS DISCOVERERS. 

tor intersects the geographic equator in several 
places : one point of intersection is in the Island 
of St. Thomas, and another in the Pacific Ocean, 
about 142° longitude east from Greenwich. This 
aclinic line is, however, constantly changing its po- 
sition. 

The magnetic poles of the earth do not coincide 
with the geographic poles. When the dipping- 
needle is held directly over the magnetic north 
pole of the globe, the needle will take a perfectly 
vertical position, the north pole of the needle 
pointing downward. If we could place the needle 
over the south magnetic pole, the needle would 
assume a perpendicular attitude, the south pole 
pointing downward. 

Sir James Ross, in 1831, trying to find a north- 
west passage around the American Continent, when 
in latitude 70° 5' 17", near Hudson's Bay, saw the 
needle take a vertical position. The south mag- 
netic pole has not been located. 

When the needle of the compass is placed in 
the immediate neighborhood of one of the mag- 
netic poles of the earth, it loses its power alto- 
gether, and points indifferently in all directions. 
If a magnetized needle be placed on a cork float- 
ing in a pool of water, after a short time the 



THE MARINER'S COMPASS. 25 

poles of the needle will so arrange themselves as 
to point permanently north and south, but the 
cork will not be drawn toward either the north or 
south 6hore. From this it is concluded that the 
influence the earth exercises upon the needle is 
not attractive, but merely directive. 

The intensity of the earth's action upon the 
magnetic needle varies in different places. The 
nearer the needle is approached to the magnetic 
poles, the more sensitive it grows, and the more 
striking and vivid its movements. As we draw 
near to the equator, the effect is seen to become 
more and more feeble. 

The intensity of the earth's magnetism is found 
to be greater in colder than in warmer climes. 
This intensity is also noticed to be greater in the 
western and northern than in the eastern and 
southern hemispheres. The earth's magnetism dis- 
plays itself with a greater intensity at the follow- 
ing places, in the order in which they are named : 
St. Petersburg, London, Berlin, Paris, Vienna, 
Madrid, Rome. 



CHAPTER III. 

MICHAEL FARADAY. 

Michael Faraday, most probably the greatest 
experimental physicist that ever lived, was the son 
of very poor parents, his father being a journeyman 
blacksmith. Michael was born at Newington Butts, 
near London, on the 22d of September, 1791 ; and, 
ten years later, necessity forced his family to seek 
public relief during a period of great distress in 
London. 

In his thirteenth year he went as newspaper-boy 
to Mr. George Riebau, a bookseller on Blandford 
Street; and in his own simple way he tells the 
hardships of this task : " It was his duty, when he 
first went, to carry round the papers that were lent 
out by his master. Often on a Sunday morning 
he got up very early and took them round, and 
then he had to call for them again ; and frequently, 
when he was told the paper was not done with, 
6 You must call again, 5 he would beg to be allowed 



MICHAEL FARADAY. 27 

to have it, for his next place might be a mile off, 
and then he would have to return back over the 
ground again, losing much time, and being very un- 
happy if he was unable to get home to make him- 
self neat, and to go with his parents to their place 
of worship." A year later he became an appren- 
tice to Mr. Riebau, and continued in his establish- 
ment for eight years. Having an extraordinary 
taste for reading scientific works, he spent every 
leisure moment in this pursuit. He was especially 
fascinated with an article on " Electricity " that he 
found in an old encyclopaedia he was employed to 
bind, and even constructed an electrical machine 
consisting principally of an old bottle, and tried to 
verify for himself by experiment the facts referred 
to in the article. 

While a journeyman book-binder, he had the 
good fortune to attend some public lectures by 
Sir Humphry Davy, then in the zenith of his 
fame. Burning with an ardent love of knowledge, 
and encouraged by a friend, he had the resolution 
to apply to Davy for employment. Sir Humphry 
at first tried to dissuade him from his object of 
following science as a profession, warning him that 
Science was a harsh mistress, and, in a pecuniary 
point of view, but poorly rewarding those who de- 



28 ELECTRICITY AND ITS DISCOVERERS. 

voted themselves to her service. But nothing could 
withstand his thorough earnestness, and Davy en- 
gaged him as chemical assistant to the Royal Insti- 
tution of Great Britain. This was the turning-point 
in his career, and thenceforth his life, with a lover's 
fervor, was dedicated to the service of science. For 
fifty-two years, with unexampled patience and a 
hero's courage, he watched and worked in Nature's 
inner sanctuary; and for forty of these years he 
kept the name of England in the first rank of sci- 
ence. 

In the latter part of 1813 he accompanied Davy 
as his amanuensis to the Continent. This journey 
occupied a year and a half, and brought him into 
contact with the most noted men of science of that 
time. Faraday was always remarkable for his 
method, and so made notes of the famous places 
he visited, and of the great scientific experiments 
he witnessed. These notes show the goodness and 
manliness of his heart, and the early perspicacity 
of his judgment. On his return to the Royal 
Institution the rapid progress he made in self-edu- 
cation was marvelous. His work for the next five 
years in the laboratory and lecture-room was 60 
brilliant as to place him by the side of the first 
chemists of the day. During this period, also, his 



MICHAEL FARADAY. 29 

life had been one of uninterrupted happiness. But 
human life is a current that must inevitably flow 
through rough and broken passages. In his thir- 
tieth year he was unjustly accused of dishonesty, in 
claiming for himself a discovery of the great Dr. 
Wollaston in magnetism. This persecution, as un- 
deserved as it was venomous, instead of injuring 
him, rather served to bring into a brighter light his 
truth and integrity. Another source of great an- 
noyance to him at the same time was the opposition 
given by Sir Humphry Davy, through a motive 
of petty jealousy, to his election as Fellow of the 
Royal Society. His conspicuous ability, however, 
triumphed over all obstacles, and on January 8, 
1824, he was all but unanimously elected. Faraday 
tells us that he sought and paid for this title, but 
it was the only one he ever afterward solicited. 

The first mark of honor paid to Faraday's sci- 
entific labors was in his thirty-second year, and 
came from the Cambridge Philosophical Society. 
The same year he was elected corresponding mem- 
ber of the French Academy of Sciences, and of 
the Accademia dei Georgofili of Florence. During 
his lifetime Faraday received ninety-five honorary 
titles and marks of merit from learned bodies 
throughout the world, all coming voluntarily and 



30 ELECTRICITY AND ITS DISCOVERERS. 

unsolicited. In his thirty-fourth year he was ap- 
pointed Director of the Laboratory of the Royal 
Society. 

Faraday always had one of the kindliest natures. 
When in the height of his fame, one of his nieces 
says of him : " In times of grief or distress his 
sympathy was always quick, and no scientific occu- 
pation ever prevented him from sharing personally 
in all our sorrows, and comforting us in every way 
in his power. Time, thoughts, purse, everything 
was freely given to those who had need of them." 

On October 17, 1831, being in his fortieth 
year, Faraday made the great discovery of his 
life, and one that will make his name famous 
t ' for all time to come. He discovered magneto- 
electricity. It was the reward of seven years of 
unceasing labor and unwavering scientific faith. 
In 1824 he had reasoned himself into the be- 
lief that this discovery was possible. Professor 
Oersted, of Copenhagen, about twelve years pre- 
viously, discovered by accident electro-magnetism, 
or, that a current of electricity, passing through 
a wire coiled around a piece of soft iron, will 
magnetize the iron. Faraday, not by accident, 
but as the consequence of a clear idea, discovered 
magneto-electricity, or that a magnet will induce 



MICHAEL FARADAY. 31 

an electric current in a coil of wire. The instant 
the magnet is inserted in the coil, it induces a 
current in one direction, and when it is with- 
drawn it induces a current in the opposite direc- 
tion. These currents are but momentary ; when 
the magnet rests in the coil, no electricity is per- 
ceptible. 

These electric discoveries of Oersted and Fara- 
day have a parallel in the history of astronomy. 
William Herschel, in sweeping the heavens with 
his telescope, fell by accident upon the planet 
Uranus, thinking it at first a comet. Urbain Le 
Yerrier, from disturbances recognized in the mo- 
tions of the known planets, computed the exact 
place and size of Neptune. As the telegraph 
is the offspring of electro-magnetism, so the elec- 
tric light is the product of magneto-electricity. 
There is the highest scientific authority for saying 
that this discovery of Faraday is the greatest ex- 
perimental result ever obtained by an investigator. 

His skill as an experimenter was so delicate 
and ingenious, and his illustrations as a lecturer 
on physics so lucid, that in these particulars 
Faraday was never excelled. He left no form of 
electricity untouched in his endeavors to identify 
them all. 



32 ELECTRICITY AND ITS DISCOVERERS. 

Although. Faraday did valuable service for 
every branch of physics, his three great discover- 
ies, magneto-electricity, voltaic induction, and defi- 
nite electro- chemical decomposition, were in elec- 
tricity. The record of his labors in electricity is 
contained in his " Experimental Researches," pre- 
served in the " Philosophical Transactions " of the 
Royal Society. 

It is, indeed, a marvel how one man could 
have accomplished the work reported in these 
papers. Faraday never had but a very small 
salary, and for the prosecution of his experiments 
he had to depend entirely on this salary, so that 
he says of himself and his assistant, "We were 
living on the parings of our own skin." 

His researches in electricity occupied him 
twenty-six years. In 1855 Professor Reiss, of 
Berlin, at that time the greatest statical electrician 
in Europe, says of these " Researches " : " What 
a wonderful work these researches are in every 
respect ! Incomparable for exhibiting the greatest 
progress for which science ever was indebted to 
the genius of a single philosopher, highly instruct- 
ive by indicating the means whereby the great 
results were found. If Newton, not quite with- 
out reason, has been compared to a man who as- 



MICHAEL FARADAY. 33 

cends to the top of a building by the help of a 
ladder, and cuts away most of the steps after he 
has done with them, it must be said that Faraday 
has left to the follower, with scrupulous fidelity, 
the ladder in the same state as he has made use 
of it." 

His biographer, Dr. Bence Jones, tells us that 
Faraday's first great characteristic as a philosopher 
was the trust which he put in facts ; and his 
second was his imagination, which sometimes rose 
to divination or scientific second-sight. The beauty 
and nobleness* of his character as a man were 
formed principally of these three great qualities — 
truthfulness, kindness, and energy. 



CHAPTER IV. 

STATICAL OR COMMON ELECTRICITY. 

The word itself, electricity, is derived from 
the Greek of amber, electron ; because it was while 
rubbing amber that the property was first per- 
ceived. For the first mention of this great natural 
agent we must go back to the writings of Thales 
of Miletus, in Asia Minor, one of the seven wise 
men of Greece, who flourished about 600 years 
b. c. This philosopher relates the fact that, when 
amber is rubbed with a silken cloth, it will at- 
tract light bodies. 

Gilbert of Colchester (1600 a. d.), Otto von 
Guericke (1672), Hawksbee (1709), and Wehler 
(1729), bring electricity down to Franklin, Gray, 
and Du Fay, who between 1730 and 1760 may 
be said to have systematized the science. 

Common electricity, also called statical, is 
generated by friction. When a tube of glass is 
briskly rubbed for the space of a few seconds 



STATICAL OR COMMON ELECTRICITY. 35 

with a dry woolen cloth, the tube will become 
excited, and, if approached toward small pieces 
of paper or cork lying on a table, will first at- 
tract them, causing them to leap toward it, and 
then repel them, sending them flying back to the 
table. Once they touch the table, the tube will 
again attract them, and again repel them, and so 
on, while the tube continues excited. 

Pieces of amber, sticks of sulphur or resin, 
when rubbed with dry flannel, will act similarly. 
If, however, a small ball of pith of elder be sus- 
pended by a long silk thread from a convenient 
support, and an excited glass tube be approached 
toward it, the tube will at first attract and then 
repel it, and will continue thereafter to repel it 
until it touches some substance in connection 
with the earth, and is thus deprived of this new 
property imparted to it by the excited tube. And 
if this pith-ball, thus repelled by the excited glass 
tube, and while still being so repelled, be ap- 
proached by a piece of sealing-wax or other resin- 
ous substance, also excited by being rubbed with 
dry flannel or silk, the ball will be instantly at- 
tracted by the sealing-wax or resin, held for a 
short space, and then repelled. If a pith-ball be 
suspended freely by a silk thread between excited 



36 ELECTRICITY AND ITS DISCOVERERS. 

glass and resin, it will oscillate between them like 
a pendulum, being alternately attracted and re- 
pelled by each. Two pith-balls suspended freely 
by silk threads and hanging close together, when 
similarly excited by a glass rod, will repel each 
other. They will also repel each other if similar- 
ly excited by a piece of sealing-wax, but if one 
be excited by rubbed glass, and the other by 
rubbed sealing-wax, they will attract each other. 
From these simple experiments it is inferred that 
there are two kinds of electric excitement, the 
one of glass, called vitreous or positive, and the 
one of resin, called resinous or negative. And 
from these same simple phenomena the great law 
of electricity has been deduced — that electricities 
of the same name repel, and those of different 
names attract each other. 

"When glass is rubbed with a woolen cloth, 
the electricity of the glass is positive, and that 
of the cloth is negative ; but when glass is rubbed 
with cat's fur, the fur is positive, and the glass 
negative. Sealing-wax becomes positive when sub- 
mitted to the friction of metallic bodies, and neg- 
ative when rubbed with most other substances. 
Thus bodies, by being rubbed with different ma- 
terials, may pass from the vitreous or positive 



STATICAL OR COMMON ELECTRICITY. 37 

to the resinous or negative class. To know the 
nature of the electricity of any rubbed substance, 
we must know with what it is rubbed. In the 
following enumeration, each substance., when rubbed 
by any one preceding it, is negatively electrified ; 
by any one succeeding it, positively: Back of a 
cat, smooth glass, woolen cloth, feathers, wool, 
paper, silk, lac, rough glass, sulphur. 

A pith-ball, suspended by a silk thread, and 
excited by rubbed glass or resin, will retain its 
electricity for a long time, if only surrounded by 
dry air; but if touched by the hand or a metal 
rod, it parts instantly with its electricity, while 
glass, resin, or silk will scarcely remove it at alL 
Some bodies, therefore, conduct electricity very 
well, and some others not so well ; although all 
bodies conduct it in some degree. So bodies are 
said to be good or bad conductors. If the elec- 
trified pith-ball be surrounded by damp air, or 
air containing vapor, instead of dry air, it will 
lose its electricity quite rapidly. Dry air is a bad 
conductor, but water is an excellent conductor, 
and so the vapor of water, when mixed with the 
air, adds to its conducting power t The following 
substances are the best conductors, and in the 
order named: The metals, charcoal, plumbago, 



38 ELEOTKIOITY AND ITS DISCOVERERS. 

pure water, moist snow, steam and smoke, vege- 
tables, and animals. Among bad or non-conduct- 
ors are resins, amber, sulphur, wax, fat, glass, 
precious stones, silk, wool, hair, feathers, cotton, 
paper, dry air, baked wood, and India-rubber. 
These latter bodies are also called insulators, for 
they insulate or confine electricity. 

An instrument by which the presence of elec- 
tricity is detected is called an electroscope. There 
are many different forms of the instrument, but 
one of the most delicate is the gold-leaf electro- 
scope. This simple apparatus consists of a glass 
jar having a short brass rod running down through 
its wooden stopper. From the end of the rod 
within the jar are suspended two gold leaves, 
hanging side by side. As soon as any electrified 
body is touched to the brass rod, it conducts the 
electricity to the gold leaves, which, being thus 
similarly electrified, mutually repel each other. 

Electrometers are instruments employed to meas- 
ure the quantity of electricity, and among the most 
ingenious is Coulomb's torsion-balance. The outer 
part of this electrometer consists of a glass cage 
having a long, slender glass neck. Down through 
this neck, and reaching to about the middle of the 
cage, runs a light film of spun glass, having at- 



STATICAL OK COMMON ELECTKICITY. 39 

tached to it a light beam of gum-lac, ending in a 
gilt pith-ball. Almost in connection with this pith- 
ball is another gilt pith-ball, the terminus of a brass 
rod coming down from the top of the cage. This 
latter ball is called the carrier-ball. The upper end 
of the glass thread terminates in a key furnished 
with an index moving around a circle graduated 
into 360°. "When an excited body touches the rod 
in connection with the carrier-ball, this ball be- 
comes electrified, and imparts some of its electricity 
to the other pith-ball. The two balls are thus simi- 
larly electrified, and the carrier-ball, being station- 
ary, repels the other ball. The key at the top is 
turned until, by twisting the glass film, the two 
balls are again brought together. The number of 
degrees through which the key has to be turned 
to overcome the repulsion is a measure of the tor- 
sion, and so is an approximate measure of the quan- 
tity of electricity. Coulomb found that two bodies, 
differently electrified, attract each other with a 
force inversely as the squares of their distances; 
and two bodies, similarly electrified, repel each 
other with a force varying inversely as the squares 
of their distances. 

A cheap and simple way of generating electrici- 
ty is by the electrophorus. It consists of a shallow, 



40 ELECTRICITY AND ITS DISCOVERERS. 

circular tray of tin, about a foot in diameter and an 
inch deep. Melted sealing-wax, or a mixture of 
two parts of shell-lac and one of Yenice turpentine, 
or, indeed, any resinous preparation, is poured into 
this tray until it is about half filled, let gradually 
cool, and made as smooth as possible. A disk of 
brass, a few inches less in diameter than the tray, 
and having a glass handle, is provided, to be placed 
over the tray. The resinous cake is briskly rubbed 
with dry flannel, and is thereby negatively electri- 
fied. The brass disk is then placed on the tray, 
whose negative electricity attracts and holds the 
positive electricity of the brass disk, thus setting 
its negative electricity free, and, if the disk be 
touched by the hand, the negative electricity will 
be carried to the earth, leaving the disk positively 
electrified. If, then, the brass disk be raised by the 
glass handle, and a conductor approached toward 
the disk, it will emit a positive electric spark. This 
process may be repeated a great number of times, 
as the negative electricity of the resin is not con- 
ducted away, but merely acts by induction on the 
brass disk. In the best form of electrophorus the 
disk, when in place, is connected with the out- 
side of the tray by means of a tiny brass rod. 
This avoids the trouble of touching the disk 



STATICAL OR COMMON ELECTRICITY. 41 

with the finger to carry off the free negative 
fluid. 

When large quantities of electricity are sought, 
an electric machine must be employed. Probably 
the best form of machine now used is the plate 
machine. This consists of a large circular plate of 
glass supported on an axis between two wooden 
uprights, and turned by a winch. Attached to the 
uprights are two pairs of cushions pressing tightly 
against the glass plate. These cushions are con- 
nected with the earth by means of small brass 
chains. The prime conductor is a hollow arm of 
brass, forming three sides of a rectangle, and insu- 
t lated on glass legs. The prime conductor connects 
with the glass plates by means of a number of brass 
points approaching to within about one eighth of 
an inch of the plate. An amalgam is applied to 
the part of the cushions in connection with the 
surface of the glass plate. Two parts of zinc and 
one of tin, melted together, and added to six parts 
of mercury, previously heated in a crucible, make 
the best amalgam for the electric machine. The 
mixture, being stirred until cold, is readily reduced 
to a fine powder, which requires merely to be 
formed into a paste with lard to be ready for use. 
When about to be used, the electric machine should 



42 ELECTRICITY AND ITS DISCOVERERS. 

be placed in a dry, warm room, the plate rubbed 
well with a woolen cloth, and a little fresh amal- 
gam applied to the cushions. By the friction of 
the plate against the cushions the electricity of the 
cushions is decomposed, the negative being carried 
off by the chains to the earth; the positive holds 
the negative of the glass, setting its positive free, 
and this free positive draws the negative of the 
prime conductor, setting its positive free. Thus 
the prime conductor is positively electrified by 
giving up its negative electricity to the glass plate. 
To work the machine to advantage, one thing is 
imperative, which is ordinarily much overlooked, 
and it is, that the cushions must be connected with 
the earth by means of a good conductor. If pos- 
sible, this connection should be made with the lead 
pipes supplying the house with water. 

For purposes of experiment, when it is desir- 
able to store a large quantity of electricity to be 
carried from place to place, we must have recourse 
to the Leyden-jar. This consists of an ordinary glass 
jar coated on the inside and on the outside with 
tin-foil to within a few inches of the top. Fitted 
to the mouth of the jar is a wooden stopper, 
through which a long brass rod is passed, termi- 
nating on the outside in a large brass knob. The 



STATICAL OR COMMON ELECTRICITY. 43 

lower end of the rod must be connected by a chain 
or other good conductor with the inside coating of 
the jar. "When the knob is touched to the prime 
conductor, the inside coating, being in immediate 
connection with it, becomes positively electrified. 
The positive electricity of the inner coating acts 
by induction through the glass on the outside coat- 
ing, decomposing its electricity, attracting and hold- 
ing fast the negative, and setting free the positive, 
which escapes by means of the hands to the earth. 
The jar must be held in the hands or otherwise 
connected by a good conductor to the earth, that 
its positive electricity may escape, or the jar will 
not be charged. There is then free negative elec- 
tricity on the tin-foil of the outside, and free posi- 
tive electricity on that of the inside, separated by 
the glass, which is a bad conductor, and so prevents 
them from uniting. If the outside coating be con- 
nected with the knob by a good conductor, the 
electricities will rush together with a vivid flash. 
"When the connection is made by means of the 
hand, we experience a shock, called the electric 
shock. The negative electricity on the outside of 
the glass, attracted and held by the positive of the 
inside, is said to be bound, and electricity so bound 
receives the name of statical. It is now the gen- 



44: ELECTRICITY AND ITS DISCOVERERS. 

eral impression that the electricities are confined 
to the surfaces of the glass jar, instead of to the 
tin-foils, and that the coatings serve merely as con- 
ductors. The coatings, when removed from the 
charged jar, give no evidence of free electricity. 
When restored to the jar, it is found that the jar 
is still charged. When the Leyden-jar will receive 
no more electricity from the prime conductor, it is 
said to be charged or saturated. 

The Leyden-jar had not only an accidental 
but a very simple origin. Cuneus, of Leyden, in 
1746, while trying to electrify a glass of water 
with a wire charged with electricity, holding the 
glass in one hand and removing the wire with 
the other, felt a sharp shock. The hand holding 
the glass acted as the outer coating, and the 
water the inside coating, of the Leyden-jar. The 
electrified wire charged the jar, and when the 
hand touched the water in withdrawing the wire, 
connection was formed between the outside and 
inside coating, completing the circuit and dis- 
charging the jar. 

A number of Leyden-jars, so arranged that all 
the outsides are united and the insides connected 
by means of the knobs, form an electric battery. 
The battery may be discharged by connecting the 



STATICAL OR COMMON ELECTRICITY. 45 

inside with the outside of any single jar. A bat- 
tery thus arranged gives great quantity, but, if 
the outside coating of each in succession be con- 
nected with the inner coating of the next, and 
the battery be discharged by joining the outer 
coating of the first with the inner of the last, 
great intensity is obtained. 

Often it is inconvenient, and sometimes even 
dangerous, to discharge an electric battery by the 
hand, so that a discharging rod is used, consisting 
of two brass arms terminating in large brass 
knobs, and joined together by a hinge. The arms 
are provided with glass handles. 

The electricity is confined entirely to the sur- 
face of the electrified body. This is easily proved 
by exciting a hollow cylinder of brass, and intro- 
ducing into its interior an electroscope. The 
interior will not give the faintest trace of excite- 
ment. 

The quantity of electricity depends altogether 
upon the superficies, and is not influenced by the 
mass. The greater the surface over which a given 
quantity or amount of electricity is spread, the 
less the potential, or tension, of the fluid. When 
two large globes of brass of equal size are insu- 
lated, and one of them is charged and then con- 



46 ELEOTEICITY AND ITS DISCOVERERS. 

nected with the other, it is found that the charge 
is equally divided between the two, and that the 
potential, or tension, of either one is only one 
half of that of the originally charged globe. 

On a spherical surface the tension of the elec- 
tricity is uniform, but electricity concentrates on 
points or projections. A prime conductor having 
a number of points will soon part with its elec- 
tricity, the air carrying it off rapidly from the 
points. 

A jet of steam issuing from a boiler will gen- 
erate large quantities of electricity. Armstrong 
contrived a steam electric machine of wonderful 
power, and called it the hydro-electric machine. 
It is safe, however, to let this apparatus alone; 
for there is always imminent danger of an ex- 
plosion. 

Is electricity a material substance, a single or 
double fluid, or a property of matter? The real 
nature of this subtile agent is unknown. In a 
latent state, it pervades all substances without 
affecting their volume or temperature, without 
adding to or subtracting from their weight ; nor 
does it interfere with the power of cohesion in 
bodies. There are two theories of electricity that 
have much prevailed — the one of Dr. Franklin, 



STATICAL OR COMMON ELECTRICITY. 47 

and the other of Du Fay. According to the 
Franklinian hypothesis, there is a single, highly 
elastic, imponderable fluid pervading all matter. 
In the unexcited state, it is uniformly distributed 
through bodies. "When a body becomes electrified, 
it either loses or gains more than its normal 
amount of the fluid. Thus, when glass is rubbed 
with silk, the glass becomes over- and the silk 
under-charged. A body overcharged is said to be 
in the positive, and undercharged in the negative 
state. The theory of Du Fay supposes two of 
these subtile fluids existing in combination in all 
substances, when in the natural or unexcited con- 
dition. These fluids are self -repellent, but attract 
each other. The friction of two bodies, such as 
glass and wool, separates the fluids, the glass tak- 
ing one and the wool the other. These fluids 
receive the names of vitreous and resinous. In 
favor of the two-fluid theory, it may be remarked 
that, when a charge is passed through a card, 
there is a burr on both sides, showing the action 
of a double force ; also, that the shape of the 
spark of positive electricity is a brush ; of the 
negative, a star. 

Dr. Faraday thought electricity a mere power 
of matter, like the attraction of gravitation; and 



48 ELECTRICITY AKD ITS DISCOVERERS. 

spent much of his time trying to show that light, 
heat, and electricity were all modifications of one 
common principle. The conviction that electricity 
is a wave of polarization, passing along conduct- 
ors, seems now to prevail with philosophers. 



CHAPTER V. 

ATMOSPHERIC ELECTRICITY. 

Ordinarily, in clear weather, the atmosphere 
is found to be slightly charged with free positive 
electricity. The first evidence of this condition 
of the air is detected by the gold-leaf or other 
electrometer, at the height of about four feet from 
the ground. The electricity of the four feet of 
intervening atmosphere is disguised, or neutral, like 
that of the glass between the outside and inside 
coating of a Leyden-jar. When the atmosphere 
has free positive, the earth's surface is found to 
have free negative, electricity; this is the conse- 
quence of induction, but whether it is the action 
of the air on the earth, or of the earth on the 
air, is not so evident, Peltier attributes it to the 
earth's surface having always some free negative 
excitement. 

As we ascend upward, the electric tension grad- 
ually increases. An innumerable number of meth- 



50 ELECTRICITY AND ITS DISCOVERERS. 

ods have been employed for testing the electric 
state of the atmosphere at all altitudes. An in- 
genious test was made on the Great St. Bernard, 
by shooting an arrow attached to a long cord cov- 
ered with tinsel, in different directions. The cord 
was also connected with a stationary gold-leaf elec- 
trometer. When the arrow was shot in a horizon- 
tal direction, the leaves were unmoved, but when 
in a vertical one, the leaves parted more and more 
as the arrow flew upward. The ordinary way of 
testing the electric condition of the air is by 
means of a long vertical pole, bearing a wire at- 
tached to an electrometer. 

The electric potential of the air is weakest be 
fore sunrise, and strongest just after sunrise ; it then 
diminishes and reaches its weakest point once more 
a few hours before sundown, after which it a sec- 
ond time increases until, during the night, it again 
attains its strongest point, and then decreases until 
near morning. The tension is greatest in fogs, and 
during frosty weather, and least in hot weather 
and just previous to rain. Atmospheric electricity 
is far more intense in winter than in summer, and 
seems to grow in force with the growth of the cold. 

When the sky is overcast, and the clouds are 
moving in different directions, the electric condi- 



ATMOSPHERIC ELECTRICITY. 51 

tion of the air varies, and sometimes very rapidly. 
Now it is negative, and in a few moments posi- 
tive, and different strata lying very close together 
may have different electric states. There are a 
great many different opinions concerning the cause 
of this free electricity in the air. The matter is 
very unsettled. Scientists have as yet arrived at 
nothing definite, some alleging one cause and oth- 
ers another. 

A combination of the causes may be the near- 
est to the truth. Combustion on the earth's sur- 
face, evaporization, animal and vegetable life, 
chemical action, friction of the air against the 
ground, and the unequal distribution of heat in 
the different strata of the air, may each, in all 
probability, add its pro rata to the electric store- 
house of the clouds. 

A cloud is a vast collection of minute hollow 
vesicles of water, and is a fair conductor of elec- 
tricity. Because they are good conductors, and so 
gather up the loose electricity, clouds usually con- 
tain a considerable quantity of it in the free state. 
When clouds differently charged come close to- 
gether, they neutralize one another by a vivid 
flash. This is the lightning-flash. When an over- 
charged cloud is neutralized by the earth, the 



52 ELECTRICITY AND ITS DISCOVERERS. 

lightning-flash is between the cloud and the earth. 
This is the flash that works mischief, and which 
is so much dreaded. 

Dr. Franklin was the first to prove the iden- 
tity of lightning with electricity. This he did at 
Philadelphia, in 1752. Every one, of course, is 
familiar with the story of Franklin's kite. It was 
fashioned after the manner of an ordinary kite ; 
silk, however, being used instead of tissue-paper. 
Connected with the string, and extending above 
the head of the kite, was a pointed iron wire. 
A key was attached to the lower end of the 
string, and to this key was tied one end of a short 
silk ribbon, whose other end was fastened to an 
upright post. The silk, being a non-conductor, 
insulated the string. This insulation was neces- 
sary ; otherwise the electricity would be con- 
ducted off imperceptibly. When the storm-cloud 
came on, the string was saturated with rain, and 
became a good conductor, so that the electric fluid 
ran down it, and, with a vivid flash, leaped to any 
conductor approached toward the key. A short 
time afterward, Romas, in France, by using a 
much longer string, received from the storm-clouds 
vivid electric flashes, ten feet long, accompanied 
by reports as loud as that of a pistol. Professor 



ATMOSPHERIC ELECTRICITY. 53 

Riehmann, of St. Petersburg, in 1753, experimented 
during a thunder-storm with a long, pointed con- 
ductor reaching high into the air. The professor 
made the insulator eight feet long, and, standing 
too close to the terminus of the conductor, a great 
charge passed through his head, singeing his waist- 
bands, bursting open his shoes, and killing him in- 
stantly. 

Two clouds, differently charged, act on one 
another by induction similarly to the coatings of 
the Leyden-jar, the air separating them taking the 
place of the glass. When they approach suffi- 
ciently close that the electric tension is powerful 
enough to overcome the resistance of the non-con- 
ducting medium between, the opposite fluids unite 
by a flash. A cloud and the earth act similarly, 
when the cloud approaches near enough to the 
earth. Clouds part with their charge to the earth 
at various heights, all depending on the force of 
their electric tension. Lightning has been ob- 
served to dart to the earth from thunder-clouds 
having a vertical height of 26,650 feet, and these 
clouds have been known to be only S3 feet from 
the ground when they emitted their spark. 

Though the vesicles of the cloud are similarly 
electrified, they do not repel one another, because 



54 ELECTRICITY AND ITS DISCOVERERS. 

of the inducting influence exercised by the neigh- 
boring cloud or the earth. When a feather is 
placed on the prime conductor, its fine fibers fly 
apart, being similarly excited ; but if the hand be 
approached toward the feathers, the repulsion dis- 
appears under the influence of the hand's induc- 
tion, and all the fibers of the feather reach out in , 
one direction toward the hand. The vesicles of a 
cloud in the vicinity of another cloud or the earth 
act similarly. Slate-gray clouds are negatively, 
and white, red, and orange-colored clouds positive- 
ly electrified. 

The lightning, or light, is caused by the re- 
sistance of the air to the passage of the electric 
discharge. The air being a non-conductor, elec- 
tricity has to force its way through it with the 
greatest violence. This violent passage of the 
current through the air causes a wonderful com- 
pression of its particles, and this compression 
produces the vivid light. Lightning is merely a 
mechanical effect of the electric current. Light- 
ning is principally of three kinds — zigzag, sheet, 
and ball lightning. The zigzag is caused by a 
discharge from a cloud at a great height from 
the earth. The fluid, in its downward journey, 
always seeks the path of least resistance. Moist- 



ATMOSPHERIC ELECTRICITY. 55 

lire is a fair conductor, and, as the distribution 
of moisture through the air is very unequal, so 
the current, in following it, must take a zigzag 
course. The zigzag streak, meeting with more 
than ordinary resistance, is broken up into two, 
three, or more streaks. Sheet-lightning is a 
broad flash unaccompanied by sound, and, for 
the most part, is from one cloud to another, or 
is sometimes the reflection of distant lightning. 
It is also called heat-lightning, as it is said to 
presage heat. 

Ball-lightning is a fearful thing indeed; much 
dreaded, and nobody knows precisely what it is. 
Many consider it a meteor that falls from the 
clouds during a more than ordinarily violent 
thunder-storm, and that it is not electricity at 
all. It is difficult, however, to understand how 
meteors can be so accommodating as to be on 
hand just when called for by these violent elec- 
tric explosions. That this globular appearance is 
due to an uninterrupted discharge of electricity, 
is the most probable opinion. This glowing ball 
will set fire to any combustible material it hap- 
pens to come in contact with ; lightning-rods are 
no protection against it; and it occupies several 
seconds in its passage. This latter fact is the 



56 ELECTRICITY AND ITS DISCOVERERS. 

kernel of the difficulty. How lightning can con- 
sume several seconds in traveling over the space 
of a few miles, is inexplicable. Wheatstone, after 
much industry with a very delicate contrivance, 
made up his mind that the velocity of electricity 
is 288,000 miles per second, and no one ever 
estimated it below 13,500 miles; so that this 
phenomenon of the fire-ball has yet to be satis- 
factorily explained. 

The distance of the lightning-flash can easily 
be computed by counting the number of seconds 
between the flash and the sound. The flash is 
instantaneous, while the average velocity of sound 
through the atmosphere at a temperature of G0° 
Fahr. is 1,125 feet per second. Ten seconds 
would show a distance of 3,750 yards, or more 
than two miles. 

The thunder, most probably, arises from the 
vibrations produced in the air by its sudden and 
violent compression. The rolling is attributed to 
echo. But thunder rolls equally on the sea as on 
the land. Driven from echo, many philosophers 
try to account for the peculiarity of the rever- 
berations by saying that, though the flash is in- 
stantaneous, still the sound, being so much slower, 
and breaking forth from all the points along the 



ATMOSPHERIC ELECTRICITY. 57 

path of the flash, reaches the ear at different 
intervals. In this case, however, thunder should 
begin at its loudest and gradually die away; be- 
cause the sound comes first from the nearest 
points, and then from points more and more dis- 
tant. On the contrary, distant thunder is just 
audible at the beginning, gradually gains in 
strength, and again grows fainter, till it dies 
away. The best explanation yet ventured seems 
to be, that the zigzag course of the flash makes 
so many different angles that the waves of sound 
sometimes intermingle and sometimes interfere, 
weakening or strengthening each other, as the 
case may be. It is said that the sound of thun- 
der has never been heard farther than fourteen 
miles from the flash, whereas the guns of Water- 
loo were heard 115 miles away. When a sharp, 
loud peal accompanies the flash, the stroke is in 
the immediate neighborhood. 

Men and animals are known to have been 
killed, although at quite a distance from where 
the lightning actually struck. This is done by 
the returning shock. When a cloud is positively 
electrified, it induces negative electricity in the 
earth's surface beneath it, and also in all objects 
on that surface. When a cloud, consequently, is 



58 ELECTRICITY AND ITS DISCOVERERS. 

heavily charged with free positive electricity, a 
man just beneath it becomes strongly charged 
with the free negative fluid, owing to induc- 
tion. Then, if a tree or other object discharge 
the cloud, restoring its electric equilibrium, there 
being nothing left in the cloud to hold the 
negative charge in the man, the negative rushes 
away from him with such violence as to kill 
him. 

Lightning-rods, or paratonnerres, owe their 
origin to Dr. Franklin. Their purpose is to 
conduct the electricity from the cloud to the 
earth silently, imperceptibly, and harmlessly. 
Electricity always selects and follows the best 
conductor. The rod should be a good con- 
ductor, and attached to the walls by wooden 
fastenings. The rod being a much better con- 
ductor than the walls, trees, or air, will be 
selected by the electric spark. The rod must 
reach above the building to be protected, be 
strictly continuous, with good and perfect join- 
ings, and run down a considerable distance into 
the moist ground. The best material is copper; 
but if iron, it must be at least three fourths of 
an inch in thickness. It should be pointed at 
the top, as points have an infinite power of con- 



ATMOSPHERIC ELECTRICITY. 59 

duction. If the joinings be poor, and the rod 
loosely put together, the current may leave it, 
and pass through the house. If the rod be too 
thin, it may be fused, in which case also the 
lightning may pass through the building. If 
there be metal gutters on the house, they should, 
for greater safety, be connected by metal strips 
with the rod. The ground end of the rod 
should run in a direction away from the build- 
ing, penetrate at least six feet into the earth, and 
terminate in powdered charcoal, both to preserve 
it from oxidizing and to improve the conduc- 
tion. The lightning-rod does not attract the 
fluid, but, when the charge must pass to the 
earth, the rod directs its course. The conducting 
power of the rod's point is so wonderful, that it 
disarms the cloud imperceptibly, stealing its thun- 
der, and preventing a flash. The rod will protect 
a space all around, the shape of a cone, whose 
apex is the top of the rod, and the radius of 
whose base is twice the length of the rod. The 
most dangerous place to stand during a thunder- 
storm is under a tree or beside a tall building, 
for man being a better conductor than the tree 
or building, the current will leave these objects 
to pass through him. Man is a fair conductor, 



60 ELECTRICITY AND ITS DISCOVERERS. 

and will be selected by the fluid in preference to 
most substances, the metals excepted ; and not 
being a perfect conductor, the fluid kills him. 
Lightning runs down the outside of a tree, be- 
cause it is a better conductor than the inside; 
and the inside of a man, because the fluids of 
the body are better conductors than the skin. 
When lightning strikes a man or an animal, it 
kills, because of the violence of the shock to the 
nervous system. In a house unprotected by a 
lightning-rod, the safest thing to do is to lie 
down in a feather-bed in the middle of a room 
in the middle story. Feathers are non-conductors, 
and the position is out of the lightning's course. 
The attic and cellar are places of danger, as the 
fluid sometimes flashes from the earth to the 
cloud, and sometimes from the cloud to the 
earth; so that these places may be directly in its 
course. Standing near the fireplace, in a draught 
near an open window or door, leaning against a 
wall, are also attended with more or less danger. 
Smoke is a conductor, and may carry down the 
fluid into a person's body. The lightning may 
run down the walls of a house, or the large 
timbers near the open door or window, and so 
leave these to pass through the human body. 



ATMOSPHERIC ELECTRICITY. 61 

To be in a crowd of persons or near a herd 
of animals is dangerous, as the ascending vapor 
is a good conductor, and so many bodies offer a 
large conducting space. The best place for a 
person outside would be twenty-five or thirty 
feet from a tree, lofty building, or stream of 
water. Lightning seldom damages ships or steam- 
boats, because water is so excellent a conductor, 
and the vessels so poor, that the fluid will not 
be diverted by them from its course ; and they 
will not be struck, unless they are in the direct 
line of the flash. 

Lightning is entirely too much feared ; the 
risk of being killed by its stroke may be said to 
be infinitely small. There is far more danger to 
be encountered in the ordinary walks of life. 
The electric flash purifies the air, by generating 
nitric acid and ozone, or tritoxide of hydrogen. 
Both these substances have a tendency to destroy 
animal and vegetable putrefactions. The elec- 
tricity of the atmosphere has a wonderful in- 
fluence on both the animal and vegetable king- 
doms, directly affecting the nervous system and 
the circulation of organic juices. Much of the 
stimulant we experience on a frosty morning is 
due to the extra quantity of electric excitement 



62 ELECTRICITY AND ITS DISCOVERERS. 

produced by the friction of the wind against the 
frosty ground. 

As Dr. Franklin gave the first impetus to 
the study of atmospheric electricity, the next 
chapter will be devoted to that great savant 



CHAPTER VI. 

BENJAMIN FRANKLIN. 

Benjamin Franklin, our own dear philoso- 
pher, was born in Boston, January 17, 1706, of 
Josiah Franklin and Abiah Folger, youngest daugh- 
ter of Peter Folger, one of the first settlers of 
Nantucket Island. At the time of Benjamin's 
birth his father was a soap-boiler and tallow- 
chandler, though his ancestors, for upward of 
three hundred years, were village blacksmiths in 
Old England. His father was very poor, and 
had seventeen children to support, yet it seems 
they were all happy. Jane, the favorite sister of 
Benjamin, said of their early home: "It was, 
indeed, a lowly dwelling we were brought up 
in, but we were fed plentifully, made comfort- 
able with fire and clothing, had seldom any 
contention among us ; but all was harmony, 
especially between the heads, and they were 
universally respected." 



64 ELECTRICITY AND ITS DISCOVERERS. 

Benjamin was early set apart by his parents 
for the Church, and with this view was sent, 
when eight years old, to the Boston Grammar- 
School. In less than a year he reached the head 
of his class. His father, however, after mature 
thought, changed his intention of devoting his 
son to the service of religion, being of opinion 
that the members of the ministry in America 
were too poorly recompensed. Accordingly, he 
was withdrawn from the Grammar-School, and 
sent for a year to George Brownwell, a master 
skilled in arithmetic and penmanship. This ended 
his school career, and when only ten years old 
his father took him into his own business of 
soap-boiling, which business the little Benjamin 
very heartily despised. His two earliest passions 
were for books and swimming. He was never 
excelled as a swimmer, and he may be said to 
have devoured books. He had the precious fac^ 
ulty of extracting from a book the one thing to 
which it owed its value. Among his first read- 
ings were Burton's "Historical Collections," Plu- 
tarch's "Lives," and Defoe's "Essay upon Pro- 
jects." 

Seeing his growing fondness for books, and 
his persistent dislike to his father's shop, his 



BENJAMIN" FKANKLIN. 65 

parents concluded to give him a trade kindred 
to his tastes. In his twelfth year he was ap- 
prenticed for nine years to his brother James, 
who was a printer. This James Franklin, August 
17, 1721, published a small newspaper, called the 
" New England Courant." It is easily understood 
that a newspaper was at that time a rarity and a 
risk, when it is considered that the first London 
newspaper appeared in 1622, the first French one 
in 1632, and the first American, at Boston, on 
the 25th of September, 1690. The young Benja- 
min had a great ambition to become a good Eng- 
lish writer. All his leisure moments on work-days 
and the greater part of Sunday were given to 
study, and he contributed several pieces surrep- 
titiously to the "Courant." When his brother 
discovered that he was the author of these con- 
tributions, which were of considerable merit, he 
became quite incensed against him, and thence- 
forth treated him with great harshness. 

In 1723, being in his eighteenth year, Benja- 
min resolved to no longer bear his brother's con- 
tinued ill usage, and, without the knowledge of 
his family, ran away to New York. Here fail- 
ing to obtain employment, after some rough ex- 
perience and much fatigue, being penniless, he 



66 ELECTRICITY AND ITS DISCOVERERS. 

made his way to Philadelphia. In this city, after 
a short struggle with adverse circumstances, he 
obtained work at the printer's trade. The un- 
worthy Governor of Pennsylvania, Sir William 
Keith, lured the young man from his work, and 
sent him, with false promises of assistance, to 
England, to pmrchase a printer's plant, that he 
might set up in business for himself. On reach- 
ing London, he discovered the perfidy of his 
supposed benefactor, and finding himself in a 
strange country, without friends, and with no 
means of returning home, he sought, and fortu- 
nately found, employment at his trade. lie 
worked in London for a year and a half, and 
then returned to Philadelphia in company with a 
merchant named Denham, with whom he had 
contracted a close friendship. On reaching Phila- 
delphia, Denham employed him as a clerk. Soon 
after, on the death of this merchant, he lost his 
clerkship, and returned to his old business of 
journeyman printer. About this time he started 
the celebrated club called the Junto, its object 
being the mutual self -culture of mechanics. It 
became very famous. In the spring of 1728, 
Franklin, by the aid of a few kind friends, was 
enabled to start a printing-office of his own. 



BENJAMIN FRANKLIN. 67 

His wonderful industry, great tact, and scrupulous 
honesty won success. Besides printing, he cast 
types, cut ornaments for title-pages, made his 
own ink, and even the lamp-black for the ink. 
Such unflagging energy as his must always pros- 
per. One of his neighbors remarked of him at 
this time : " The industry of that Franklin is 
superior to anything I ever saw of the kind. I 
see him still at work when I go home from the 
club, and he is at work again before his neigh- 
bors are out of bed." Franklin published the 
"Pennsylvania Gazette," October 2, 1729. This 
undertaking almost overwhelmed him, and it re- 
quired two years of most severe and incessant 
struggle to reach a position of financial safety. 
In those days of Franklin's youth it was truly a 
difficult task for a poor young man to win his 
way to prosperity. On September 1, 1730, he 
wedded Deborah Read, a truly noble woman, 
who proved a precious helpmate to him. Shortly 
after his marriage, he founded the Library of 
Philadelphia, one of the most useful institutions 
of its kind that ever existed ; and so great and 
lasting was its success that, in 1861, it contained 
seventy thousand volumes. 

In December, 1732, Franklin first published 



68 ELECTRICITY AND ITS DISCOVERERS. 

his almanac containing the sayings of "Poor 
Richard," which became famous all the world 
over. In 1736 he was elected Clerk to the Gen- 
eral Assembly, and the following year appointed 
Postmaster of Philadelphia. 

Amid all his arduous duties he was carrying 
on the work of mental and moral self-improve- 
ment with the greatest assiduity. In his seventy- 
ninth year, Franklin wrote : " It may be well 
my posterity should be informed, that to this 
little artifice, with the blessing of God, their 
ancestor owed the constant felicity of his life 
down to the seventy-ninth year, in which this 
is written. What reverses may attend the re- 
mainder is in the hand of Providence ; but if 
they arrive, the reflection on past happiness en- 
joyed ought to help his bearing them with more 
resignation. To temperance he ascribes his long- 
continued health, and what is still left to him of 
a good constitution. To industry and frugality, 
the early easiness of his circumstances and acqui- 
sition of his fortune, with all that knowledge that 
enabled him to be a useful citizen, and obtained 
for him some degree of reputation among the 
learned. To sincerity and justice, the confidence 
of his country, and the honorable employs it con- 



BENJAMIN FRANKLIN. 69 

ferred upon him ; and to the joint influence of 
the whole mass of the virtues, even in the im- 
perfect state he was able to acquire them, all 
that evenness of temper and that cheerfulness 
in conversation which makes his company still 
sought for, and agreeable even to his young ac- 
quaintance." 

It was Franklin's virtue, more even than his 
great erudition, that made him revered and be- 
loved for four generations. In 1744 he founded 
the Philadelphia fire system, which, under his 
guidance, soon attained great excellence. In 1746 
Franklin began his studies and experiments in elec- 
tricity. Electricity was then the rage throughout 
the civilized world. Cuneus, of Leyden, had just 
discovered the principle of the Leyden-jar. Frank- 
lin received from one of his friends in England a 
glass tube for generating the electric fluid. The 
tubes then used were two feet and a half long, 
and the rubber either cloth or buckskin. He 
devoted himself unreservedly to the study of this 
subtile agencv. In 1747 he wrote : " I never 
was before engaged in any study that so totally 
engrossed my attention and my time as this has 
lately done ; for, what with making experiments 
when I can be alone, and repeating them to my 



70 ELECTRICITY AND ITS DISCOVERERS. 

friends and acquaintance, who, from the novelty 
of the thing, come continually in crowds to see 
them, I have, during some months past, had 
little leisure for anything else." He frequently 
experimented with points, whose great power to 
draw off the fluid from bodies greatly engaged 
his attention. One of his first conjectures was, 
that electricity was not created, but only collected, 
by friction, and he soon reached his positive and 
negative theory ; or, that electricity is a single 
subtile fluid, existing in all bodies, latent when 
unexcited, but, when these bodies are excited, 
having more or less than their normal quantity. 
Owing to his isolation from European philoso- 
phers, and unacquainted with their discoveries, he 
made many beautiful experiments, which, although 
previously made by them, were original with him. 
In 1749 he drew up a series of fifty-six obser- 
vations, entitled " Observations and Suppositions 
toward forming a new Hypothesis for explaining 
the Several Phenomena of Thunder-gusts." The 
most celebrated of all his electric writings soon 
followed, and that which made his name forever 
famous in the world of science : it was entitled 
" Opinions and Conjectures concerning the Prop- 
erties and Effects of the Electrical Matter, and 



BENJAMIN FRANKLIN. 71 

the Means of preserving Buildings, Ships, etc., 
from Lightning, arising from Experiments and 
Observations made at Philadelphia, 1749." The 
two suggestions that will connect the name of 
Franklin for all time with electricity are in- 
cluded in one short passage. After detailing the 
results of an experiment, in which a miniature 
lightning-rod had conducted away the fluid from 
an artificial thunder-storm, he says : " If these 
things are so, may not the knowledge of this 
power of points be of use to mankind, in pre- 
serving houses, churches, ships, etc., from the 
stroke of lightning, by directing us to fix, on the 
highest part of those edifices, upright rods of 
iron made sharp as a needle, and gilt, to pre- 
vent rusting, and from the foot of those rods, a 
wire down the outside of the building into the 
ground, or down round one of the shrouds of a 
ship, and down her side till it reaches the water? 
"Would not these pointed rods probably draw the 
electrical fire silently out of a cloud before it 
came nigh enough to strike, and thereby secure 
us from that most sudden and terrible mis- 
chief?" 

He gives the steps by which he proved the 
identity of lightning and electricity. "Electrical 



72 ELECTRICITY AND ITS DISCOVERERS. 

fluid agrees with lightning in these particulars: 
1. Giving light. 2. Color of the light. 3. Crooked 
direction. 4. Swift motion. 5. Being conducted 
by metals. 6. Crack or noise in exploding. 7. Sub- 
sisting in water or ice. 8. Rending bodies it passes 
through. 9. Destroying animals. 10. Melting met- 
als. 11. Firing inflammable substances. 12. Sul- 
phureous smell." 

He had labored indefatigably in this science 
for six years, and had already convinced himself 
of the identity of the electricities of the clouds 
and the machine, before he made his kite-experi- 
ment in the spring of 1752. His son, then a 
young man of twenty-two years, was his only 
witness of the experiment. Just before the ap- 
proach of a thunder-storm, he raised the silken 
kite on that part of the Philadelphia commons 
corresponding to the present corner of Race and 
Eighth Streets. The experiment proved a com- 
plete success, and made Benjamin Franklin the 
happiest philosopher in Christendom. 

The philosophers of France were the first to 
recognize the value of Franklin's discoveries, and 
many similar experiments were made by them, 
confirming the truth of his results. He was now 
elected a member of the Royal Society of Eng- 



BENJAMIN FRANKLIN. 73 

land, and awarded the Copley medal. Tale and 
Harvard Colleges conferred upon him the degree 
of Master of Arts. He founded, about this time, 
the University of Pennsylvania and the Pennsyl- 
vania Hospital. Franklin was the first to dis- 
cover that plaster of Paris is a fertilizer. He 
first detected the poisonous properties of air ex- 
haled from the lungs, and was the first to write 
effectively upon ventilation. 

Franklin's political career began when he was 
forty-six years of age. He became successively 
justice of the peace, a member of the Common 
Council, an alderman, and a member of the As- 
sembly. He was not an orator, but he was 
effective as a speaker through his inimitable 
power of illustration and the weight of his 
character. 

Having held the place of Postmaster of Penn- 
sylvania for sixteen years, he was appointed, in 
1753, Postmaster-General for America. He greatly 
improved the postal service, and some of his im- 
provements remain a part of the United States 
system to this day. 

In 1756 Franklin was chosen agent to Great 
Britain for the Province of Pennsylvania, and 
immediately set out for England. On his arrival 

4 



74: ELECTRICITY AND ITS DISCOVERERS. 

in London, he received congratulatory letters from 
the electricians of France, Germany, Holland, and 
Italy. 

In London he continued to prosecute with 
vigor his researches in electricity ; and in the 
spring of 1759, while on a visit to Scotland, the 
degree of Doctor was conferred upon him by the 
University of St. Andrews. During this visit, 
the Scotch paid him great honor, the corporation 
of Edinburgh giving him the freedom of the 
city. Nor did he neglect the other sciences. 
He rendered valuable assistance to Adam Smith 
in his "Wealth of Nations." lie experimented 
much on heat and its conductors. One of these 
experiments in caloric he describes in this simple 
style : " I took a number of little square pieces 
of broadcloth from a tailor's pattern-card, of vari- 
ous colors. There were black, deep blue, lighter 
blue, green, purple, red, yellow, white, and other 
colors, or shades of colors. I laid them all out 
upon the snow in a bright, sunshiny morning. 
In a few hours, the black, being warmed most 
by the sun, was sunk so low as to be below the 
stroke of the sun's rays; the dark blue almost as 
low, the lighter blue not quite so much as the 
dark, the other colors less as they were lighter; 



BENJAMIN FRAXKLIX. 75 

and the quite white remained on the surface of 
the snow, not having entered it at all. What 
signifies philosophy that does not apply to some 
use? May we not learn from hence, that black 
clothes are not so fit to wear in a hot, sunny 
climate or season, as white ones?" 

After an absence of six years, he returned to 
his home in Philadelphia, November 1, 1762. 
New complications arising between the Governor 
and Assembly, Franklin was almost immediately 
reappointed English agent for the Province of 
Pennsylvania. His brilliant examination at the 
bar of the House of Commons, and his strenuous 
efforts for the repeal of the Stamp Act, had the 
effect of repealing that truly obnoxious measure. 
Georgia, New Jersey, and Massachusetts soon 
after appointed him their London agent. Find- 
ing his endeavors fruitless to arrest the quarrel 
between England and her American colonies, he 
returned to Philadelphia in 1775, after an absence 
of ten years. Franklin's reputation was at this 
time very great and extensive. He was incom- 
parably the foremost man of America, a member 
of every important learned body in Europe, a 
manager of the Poyal Society of England, Presi- 
dent of the American Philosophical Society, and 



76 ELECTRICITY AND ITS DISCOVERERS. 

one of the eight foreign members of the Acade- 
my of Sciences of France. Three editions of 
his philosophical works had appeared in Paris, 
and a beautiful new and enlarged edition in 
London. 

After the Declaration of Independence by the 
United Colonies, Franklin was appointed minister 
by Congress to represent this country at the 
French court. He devoted his whole heart and 
all his great mental power to obtain the aid of 
France in behalf of his beloved and struggling 
country; and succeeded in inducing that govern- 
ment to form an offensive and defensive alliance 
with the States. 

His renown in France was marvelous. M. 
Lacretelle, the French historian, says of him : 
"Men imagined they saw in Franklin a sage of 
antiquity, come back to give austere lessons and 
generous examples to the moderns. They per- 
sonified in him the republic, of which he was 
the representative and the legislator. They re- 
garded his virtues as those of his countrymen, 
and even judged of their physiognomy by the 
imposing and serene traits of his own. Happy 
was he who could gain admittance to see him in 
the house which he occupied. This venerable 



BENJAMIN FRANKLIN. 77 

old man, it was said, joined to the demeanor of 
Phocion the spirit of Socrates." 

"Franklin's reputation," says John Adams, 
"was more universal than that of Leibnitz or 
Newton, Frederick or Yoltaire ; and his character 
more beloved and esteemed than any or all of 
them." 

On the 20th of January, 1783, Franklin had 
the supreme happiness of signing, together with 
John Adams and John Jay, on the part of the 
United States, a treaty of peace with Great Brit- 
ain. This ended the war between these coun- 
tries. 

Franklin was at this time the most distin- 
guished man in Europe. He was the first to 
discover that the atmosphere of Europe is damper 
than that of America, and he was led to this ob- 
servation from the uniform shrinking in America 
of the wooden instrument-cases made in Europe. 
He was the first to perceive that the Gulf Stream 
is warmer than the surrounding ocean, and that 
this stream is not phosphorescent. 

In the spring of 1779 Dr. Franklin read a 
paper on the aurora borealis before the French 
Academy of Sciences. This is considered one of 
the best of his scientific writings. He attributes 



78 ELECTKICITY AND ITS DISCOVERERS. 

the aurora borealis to electricity. The following 
are the essential points of this paper: " Water, 
though naturally a good conductor, will not con- 
duct well, when frozen into ice by a common 
degree of cold ; not at all, where the cold is ex- 
treme. 2. Snow, falling upon frozen ground, 
has been found to retain its electricity, and to 
communicate it to an isolated body, when, after 
falling, it has been driven about by the wind. 
3. The humidity contained in all the equatorial 
clouds that reach the polar regions, must there 
be condensed and fall in snow. 4. The great 
cake of ice that eternally covers those regions 
may be too hard frozen to permit the electricity, 
descending with that snow, to enter the earth. 
5. It will therefore be accumulated upon that 
ice." 

Sir Humphry Davy remarks of Franklin's elec- 
tric writings: "A singular felicity of induction 
guided all Franklin's researches, and by very 
small means he established very grand truths. 
The style and manner of his publication on elec- 
tricity are almost as worthy of admiration as the 
doctrine it contains. He has endeavored to re- 
move all mystery and obscurity from the subject. 
He has written equally for the uninitiated and 



BENJAMIN FRANKLIN. 79 

for the philosopher ; and he has rendered his 
details amusing as well as perspicuous, elegant as 
well as simple. Science appears in his language 
in a dress wonderfully decorous, the best adapted 
to display her native loveliness. He has in no 
instance exhibited that false dignity, by which 
philosophy is kept aloof from common applica- 
tions; and he has sought rather to make her a 
useful inmate and servant in the common habita- 
tions of man, than to preserve her merely as an 
object of admiration in temples and palaces." 

A curious anecdote is told by Parton, his 
biographer, of a consequence of his constant love 
of experimenting: "While living in France, he 
sometimes extemporized an JEolian harp by stretch- 
ing a silken string across some crevice that ad- 
mitted a current of air. On revisiting a village, 
after the lapse of several years, he found the 
house in which he had formerly lodged deserted, 
from its having gained the ill repute of being 
haunted. Strange, melodious sounds, he was told, 
could be heard in its empty rooms. On entering 
the house he found some shreds of the silk still 
remaining, which had caused all the mischief." 

Dr. Franklin returned to Philadelphia in 17S5, 
after an absence in France of nine years. On 



80 ELECTEICITY AND ITS DISCOVERERS. 

his return, he was elected three times successively 
President of the Supreme Executive Council for 
the city of Philadelphia, was one of the principal 
framers of the Constitution of the United States, 
and retired from public life in 1788. At eleven 
o'clock at night, April IT, 1790, surrounded by 
his family and intimate friends, he departed this 
life, aged eighty-four years, three months, and 
eleven days. 

Benjamin Franklin was a noble patriot and 
truly great philosopher; great as a man of busi- 
ness, a man of science, and a statesman. Well 
has a famous Frenchman said of him, "Eripuit 
coelo fulmen, sceptrumque tyrannis" (he snatched 
the thunderbolt from the sky, and the scepter 
from tyrants). 



CHAPTER VII. 

GALVANISM, OR THE ELECTRICITY OF CHEMICAL 
ACTION. 

In 1790, Galvani, in experimenting with the 
legs of a frog, observed that, when two different 
metals, as copper and iron, one touching the 
nerves and the other the muscles of these legs, 
came in contact, it caused the most violent con- 
vulsions and twitchings in the limbs. Galvani 
located this electrical excitement in the legs 
themselves, believing that the contact of the 
metals simply discharged the electricity of the 
legs, and thus produced the convulsions. 

Yolta, of Pavia, in 1792, attributed the elec- 
tric development to the contact itself of different 
metals, and succeeded in producing an electric 
current by replacing, between the metals, the 
limbs of the frog by a moistened cloth. 

Fabroni, of Florence, in the same year, first 



82 ELECTRICITY AND ITS DISCOVERERS. 

suggested chemical action as the generator of the 
electricity in these experiments. 

When a small strip of copper and one of zinc 
are placed in a glass vessel containing acidulated 
water, so long as the metals are held upright 
and apart, no action is perceptible, nor is there 
any evidence of electric excitement ; but so soon 
as the metals are joined together, or connec 
by a wire or other good conductor, it is instantly 
noticed that bubbles of hydrogen gas are given 
off at the copper plate; while, if a magn< 
needle be held close to the connecting wire, it 
will be disturbed, or, if an electroscope be made 
a part of the circuit, it will give evidence of the 
presence of electricity. This simple arrangement 
is called a galvanic pair. The electric action will 
continue as long as the metals are connected ; 
but, if the connection be broken, the action will 
instantly cease. The acid used in this simple ex- 
periment is dilute sulphuric acid, one part of acid 
to eight or ten parts of water. The action begins 
at the bottom of the zinc plate. The zinc decom- 
poses the dilute acid, taking the acid with its nega- 
tive electricity, forming sulphate of zinc ; the posi- 
tive of the zinc combining with the negative of 
the acid, setting the negative of the zinc free, 



GALVANISM. 83 

which runs up the zinc plate, and manifests 
itself at the external end of that plate, thus 
forming the negative pole of the pair. In the 
mean time, the action of the zinc on the dilute 
acid sets its hydrogen free in a polarized state, 
its positive pole facing toward the copper. This 
liberated hydrogen attacks the neighboring atom 
of the dilute acid, taking the acid with its nega- 
tive electricity, and setting the hydrogen free, 
with its positive pole directed as before. This 
particle of hydrogen attacks the next atom of 
acid, and so on, until the copper plate is reached, 
when the hydrogen, having no affinity for the 
copper, escapes in bubbles; previously, however, 
the positive of the hydrogen takes the negative 
of the copper, setting its positive free, which, 
running up the copper plate, forms the positive 
pole of the pair. This whole action is in the 
nature of convection, and is entirely invisible ; 
the escape of the hydrogen bubbles at the copper 
pole and the gradual waste of the zinc being 
alone perceptible. 

The zinc is the active principle of the pair, and 
called the electro-positive element ; the copper serv- 
ing only to gather and conduct the electricity, 
and called the electro-negative element. If, after 



84 ELECTRICITY AND ITS DISCOVERERS. 

the pair has operated for some time, the copper 
be taken out and weighed, it will be found to 
have lost none of its weight ; the zinc, on the 
contrary, will be found to have lost in weight, 
having been dissolved by the acid to form sul- 
phate of zinc. In forming a pair, it is necessary 
to choose two metals having different oxidizable 
powers ; that is, one must have a greater affinity for 
the acid employed than the other. Thus, if copper 
had the same affinity for combining with sul- 
phuric acid that zinc has, there would be no elec- 
trical development. If two plates of zinc were 
used, or two plates of copper, there would be no 
evidence of electrical excitement. The electro- 
motive force of a pair, as it is called, or its power 
to generate electricity, is the difference between 
the affinity of the zinc and that of the copper 
for the acid ; for copper has an affinity for sul- 
phuric acid, as well as the zinc, though in a less 
degree, and the difference of these affinities con- 
stitutes the strength of the pair. 

The more dissimilar the metals are in this re- 
spect, the greater will be the electro-motive force 
of the pair. Thus, zinc and silver would be much 
more powerful than zinc and copper, because the 
silver has less affinity for the acid than the cop- 



GALVANISM. 85 

per ; and zinc with platinum would be still bet- 
ter. 

If strong water of ammonia bad been used in- 
stead of dilute sulphuric acid, the copper and zinc 
would change places : the copper, having a greater 
affinity than zinc for the ammonia, would become 
the electro-positive element and the negative pole 
of the pair. So that, in judging of the behavior 
of a galvanic pair, the liquid, as well as the met- 
als, must be considered. 

In all cases where zinc is used for galvanic 
purposes, it is amalgamated, or coated with mer- 
cury. The zinc of commerce is so very impure 
that the acid acts upon it incessantly, even when 
disconnected with the other metal, or when no 
current is flowing, thus unnecessarily wasting it 
away by local action. This local action takes place 
and consumes the zinc, without the generation of 
electricity for the common current. To prevent 
this local action and reduce the surface of the 
zinc to one uniform electric condition, the zinc 
is amalgamated. This protects the zinc from the 
action of the acid, until connection is formed be- 
tween the metals, or until and during the passage 
of the electric current. The zinc is amalgamated 
by rubbing on the mercury with a brush or cloth, 



86 ELECTRICITY AND ITS DISCOVERERS. 

or simply by pouring a small quantity of mercury 
into the acidulated water, and it will of its own 
accord amalgamate the zinc. 

"While a positive electric current is passing 
from the zinc to the copper by way of the liquid, 
and thence back to the zinc through their points 
of contact, a negative current is passing in the 
opposite direction from the copper to the zinc. 
We have the most positive evidence of the pas- 
sage of these currents. If the metallic strips be 
four inches long and two broad, and connected by 
a piece of very fine platinum wire half an inch 
in length, the wire will become brilliantly ignited, 
from the electric discharge taking place through it ; 
and this wire will retain its brilliancy so long as 
the chemical action continues. The metal strips 
are called the electro-motors. Though other bodies 
than metals may be used as electro-motors, still 
metals are the best. When zinc and copper are 
used as the electro-motors, zinc is the generator, 
and is called, as before stated, the electro-positive 
element, but is the negative pole. When copper 
and silver are used, copper is the generator, and 
so the electro-positive element, and negative pole. 
The behavior of a metal depends altogether upon 
the nature of the other metal used with it — the 



GALVANISM. 87 

metal more readily oxidizable being the electro- 
positive element, or negative pole of the galvanic 
pair. In the following list, any metal, when used 
with the ones succeeding it, will be the electro- 
positive element, and the electro-negative with 
any preceding it : zinc, lead, tin, iron, copper, 
silver, gold, platinum, and charcoal. The further 
apart they are in this list, the more powerfully 
will they act together. The strongest combina- 
tion is zinc and charcoal. 

Muriatic acid, common salt, or other liquid 
compound that acts upon zinc, may replace the 
sulphuric acid. The quantity of electricity evolved 
increases with the surface exposed to the action of 
the fluid in which it is immersed. The best way 
to construct a pair is to have the copper in a cir- 
cular form surrounding the zinc, as in this way 
all the evolved electricity is gathered up and util- 
ized. Galvanic electricity is also called dynamic, 
or electricity in motion, in contradistinction to 
frictional, which is said to be statical, or bound. 
This distinction is not, however, of an absolute 
character, because frictional electricity sometimes 
forms a current, as in its passage from the cush- 
ion of the electric machine to the earth, and gal- 
vanism may be made to overcome slight resist- 



88 ELECTRICITY AND ITS DISCOVERERS. 

ances. Still, frictional electricity is noted for its 
tension, and galvanism for its quantity. The quan- 
tity of galvanic electricity is increased by increas- 
ing the exposed surfaces of the metal electro- 
motors, but its tension is increased by joining to- 
gether several galvanic pairs. In using several 
pairs together, the zinc of one pair should be 
connected with the copper of another, and the 
zinc of this with the copper of the next, and so 
on, until the zinc of the last pair is reached, 
which should be connected with the copper of 
the first. 

The single pair produces a greater effect upon 
the needle, and has a greater heating power ; while 
the combination has a higher tension, and greater 
power to decompose chemical compounds. No 
single pair can impart a shock or decompose a 
fluid. The current of the combination seems to 
owe its intensity to the momentum imparted to 
it by the overcoming of the resistances of the 
many liquids, or media, through which it has to 
force a passage. 

In the very best arranged galvanic pairs or 
combinations the whole of the generated elec- 
tricity is not gathered into the current. The 
strength of the current suffers from one loss or 



GALVANISM, 89 

another. Professor Ohm, of Nuremberg, has 
mathematically investigated the force of currents, 
and supplied us with the laws governing their 
transmission. Supposing S to represent the actual 
strength of the current at the end of the con- 
ducting wire; F, the whole electric force gener- 
ated by the dissolving of the electro-positive ele- 
ment; R, the resistance of the fluid contained 
between the metals to the passage of the current ; 
E, the external resistance from conducting wire; 
then Ohm's simple but celebrated formula is : 

F 
R-f E 

If R be very small compared with E, R may 
be omitted, and the formula is reduced to 

F 

S— 

E 

The resistances of wires of the same material 
and of uniform thicknesses are in the direct ratio 
of their lengths, and in the inverse ratio of the 
squares of their diameters. Thus, a wire of a 
certain length offers only one half the resistance 
of one twice its length ; and a wire of a certain 
diameter will offer four times the resistance of 
one of twice its diameter. The longer the wire, 



90 ELECTRICITY AND ITS DISCOVERERS. 

the greater the resistance; the thicker the wire, 
the less the resistance. 

Almost from the very birth of galvanism, 
there have been two theories claiming to account 
for its cause. They are called the contact theory 
and the chemical theory. Those who maintain 
the former say that the electricity is produced 
by the simple contact, or touch, of the hetero- 
geneous metals. The latter theorists attribute the 
presence of the electricity to the chemical affin- 
ity of the acid for the metal. The supporters of 
these theories have waged a lively war from the be- 
ginning. An experiment of Faraday's has done a 
great deal toward establishing the chemical theory. 
He used platinum and iron as the metals, and 
sulphuret of potassium as the liquid. When the 
wires were connected, there was not the faintest 
evidence of electricity ; but when a cloth moist- 
ened with dilute sulphuric acid was placed just 
between the connecting wires, an electric current 
was instantly perceived to pass. When the zinc 
and copper are simply touched together, without 
the employment of acid, or even water, we may 
presume that there is some feeble (very feeble in- 
deed) chemical action, owing to the affinity of the 
oxygen of the air for zinc. Hence, it is almost 



GALVANISM. 91 

evident that the origin of galvanism is chemical 
action. 

A galvanometer is an instrument for measur- 
ing the strength of a galvanic current. The as- 
tatic galvanometer is sufficiently sensitive for or- 
dinary purposes, and is thus constructed : Two 
compass needles are joined together, one above 
the other, but perfectly parallel, and having their 
poles diametrically opposite. This double needle 
is suspended by a silk thread within a glass case, 
with the lower needle running along inside an 
oblong coil of wire, in the same direction as the 
wire. The lower needle has been let into the 
coil by means of a slit in the coil, and the up- 
per needle runs over a graduated scale. When 
a current of electricity runs along a wire parallel 
to a compass-needle, the needle is deflected from 
its meridional direction to the right or left, ac- 
cording as the current is positive or negative. 
Ampere gives the following rule : u Suppose the 
diminutive figure of a man to be placed in the 
circuit, so that the current shall enter by his feet 
and leave by his head ; when he looks with his 
face to the needle, its north pole always turns to 
his left." The wire in all cases is supposed to 
run along in the direction of the magnetic merid- 



92 ELEOTKICITY AND ITS DISCOVERERS. 

ian. "When a single electrified wire thus runs 
over and parallel to a needle, it will slightly de- 
flect the needle ; and, if the same wire is bent 
and doubled back under the needle, the deflection 
will be doubled, according to Ampere's rule. 
The greater the number of wires, the greater the 
deflection ; so that a coil will produce a consider- 
able deflection. The directive force toward the 
north being also absent in the double needle, the 
sensitiveness of the instrument is greatly enhanced. 
The degrees on the graduated scale show the 
comparative strength of currents. 

The voltameter is an apparatus invented by Far- 
aday, for the purpose of measuring the strength 
of currents. This is a most perfect test of a 
current's power, and is considered absolute. Two 
small pieces of platinum are placed in a bottle con- 
taining water slightly acidulated with sulphuric 
acid. Wires are soldered to the platinum pieces, 
run up through the cork of the bottle, and ter- 
minated in binding-screws. The bottle has a tube 
running up through another part of it, into a 
trough of mercury. A glass tube filled with 
mercury, having a graduated scale, empties into 
this trough of mercury. When the binding-screws 
are connected with a galvanic circuit, the water 



GALVANISM. 93 

is decomposed in the bottle into its elements of 
oxygen and hydrogen. These gases escape up 
through the trough, and into the tube containing 
the mercury, and forcing out the mercury, occu- 
py its place in the top of the tube. The grad- 
uation shows the amount of gas set free, by any 
strength of current, in any given time. 



CHAPTER VIII. 



GALVANIC BATTERIES. 



The combination of several galvanic pairs forms 
a galvanic battery. Volta constructed the first bat- 
tery, which was also called a " pile," from the pe- 
culiarity of its formation. It consisted of alternate 
plates of zinc and copper, with the interposition 
of layers of cloth saturated with acidulated water. 
The series proceeded in this wise : Copper, zinc, 
cloth ; copper, zinc, cloth ; and so on, through 
thirty or forty alternations. The first copper must 
be connected by wire with the last zinc, to com- 
plete the circuit. The generation of the current, 
in Volta's arrangement, depends on chemical action. 
When the moisture of the cloths has completely 
evaporated, the action ceases. To make up for 
the evaporation of the moisture in the voltaic 
pile, Cruikshank constructed a battery in which 
zinc and copper are soldered together in hollow 



GALVANIC BATTERIES. 95 

squares, and placed in a wooden trough. All the 
zincs face one way, and the coppers the opposite ; 
and the trough is filled with dilute sulphuric acid 
— one part acid to sixteen of water, for weak action. 
The last zinc is joined to the first copper. 

Smee's battery consists of two thin rectangular 
plates of zinc, clamped to a piece of non-conduct- 
ing wood. Between the zinc plates is placed a 
small silver slip, running into a groove in the 
wood. The zinc and silver are insulated from 
one another. Both the zinc and silver, however, 
have binding-screws, and can be joined by a 
conducting-wire, when so desired. The clamped 
plates are placed upright, in a glass cell contain- 
ing a single fluid, dilute sulphuric acid, one part 
acid to eight or ten parts water. The silver, in 
this arrangement, takes the place of the copper 
in the simple pair, and acts as the positive pole 
of the battery. 

Bubbles of hydrogen gas adhere with great 
tenacity to smooth, polished metallic surfaces, and 
thus ordinarily interfere with the action of the 
battery, by forming a film of gas between the 
silver and the acid, and so impede the usefulness 
of the battery. To obviate this drawback, the 
surface of the silver is roughened, by throwing 



96 ELECTRICITY AND ITS DISCOVERERS. 

down on it, by means of a galvanic current, 
platinum, in a state of fine division, called plati- 
num-black. By tliis means the surface of the 
silver presents an innumerable number of small 
points, from which the bubbles of hydrogen are 
readily given off, thus facilitating the action of 
the battery. This is a very cheap battery, very 
easily managed, and is constant for a long time. 

In batteries where a single fluid, as dilute 
sulphuric acid, is used, the escape of the hydro- 
gen at the positive pole greatly impedes and 
enfeebles their efficiency. By using a metallic 
oxide, the metal will be replaced in combination 
by hydrogen, and so the metal, instead of hydro- 
gen, will be carried over, and precipitated on the 
copper plate. Dilute sulphuric acid should be 
near the zinc, and the oxide near the copper. 
To prevent the fluids from mixing up, and so 
bringing the oxide into the neighborhood of the 
zinc, and thus retarding its activity, two cells 
must be employed, one for the acid and the 
other for the oxide. 

Daniell's battery is made up of an outer 
cylindrical cell of copper, in which is placed a 
smaller cell of porous earthenware, and in this a 
solid cylinder of amalgamated zinc. Into the 



GALVAKIC BATTERIES. 97 

outer cell of copper is poured a solution of sul- 
phate of copper, and into the porous vessel con- 
taining the zinc, dilute sulphuric acid, one part 
acid to eight of water. To complete the circuit, 
a wire connects the zinc with the copper. 

The acid in the porous cell attacks the zinc, 
forming sulphate of zinc, and the hydrogen being 
set free, is driven, by the influence of convection, 
through the porous cell, in among the sulphate of 
copper, which it decomposes, taking the oxygen, 
producing water, and precipitating metallic copper 
in bright crystals, with positive electricity, upon 
the copper plate. DanielPs is the most useful 
battery for telegraphic purposes, on account of 
its cheapness, easy management, and great con- 
stancy. 

In telegraphic offices the ordinary form of 
Daniell's battery differs some little from the 
above; the outer cell being of glass, into which 
a hollow cylinder of zinc is set, and into this the 
porous cell, with a solid rod of copper. The 
copper is immersed in sulphate of copper solu- 
tion, and water simply is poured into the outer 
cell containing the zinc. The water surrounding 
the zinc becomes in a short time acidulated, the 
acid of the sulphate permeating the porous cyl- 

5 



98 ELECTKIOITY AND ITS DISCOVERERS. 

inder. In the copper cell of this battery soine 
pieces of solid sulphate of copper, the blue vitriol 
of commerce, are placed on a perforated shelf, in 
order to sustain the saturation. 

This battery of Daniell has some drawbacks, 
the chief of which is that, after long-continued 
action, copper works its way to the porous cell, 
where it is deposited, closing the pores and im- 
peding the passage of the hydrogen. 

Several improvements have been made upon 
this battery, without, however, altering the prin- 
ciple of action. Siemens-Halske's is a modifica- 
tion of Daniell's, the diaphragm dividing the cells 
being a preparation of paper, instead of the porous 
earthenware. 

The Meidinger battery is also a modification 
of Daniell's, the porous cell being replaced by a 
glass funnel, through an aperture in which the 
sulphate of copper passes slowly down by its 
own weight into a copper vessel. This copper 
vessel is located at the bottom of a much larger 
glass vessel, filled with a solution of Epsom salts, 
and also containing a disk of zinc. 

The gravity battery is another modification 
of Daniell's, and is constructed on the principle 
that sulphate of copper is heavier than sulphate 



GALVANIC BATTERIES. 99 

of zinc. In the bottom of a large glass cell is 
placed a circular disk of copper, on which is 
poured a solution of sulphate of copper; over 
the solution of sulphate of copper is poured a 
solution of sulphate of zinc, and in this last fluid 
is immersed a zinc disk, with fixtures to attach 
it to the top of the glass. The solution of sul- 
phate of zinc is so much lighter than that of 
sulphate of copper, that the former fluid will 
remain on the top. 

This arrangement requires the most delicate 
nursing. It will not suffer the merest movement 
without mixing the fluids ; and it must be kept 
in a dry, warm place. 

The Menotti, Sir "William Thomson's, and the 
Muirhead batteries act on the Daniell principle. 

Grove's platinum battery is the most powerful 
and energetic of all galvanic contrivances. The 
outer vessel is a glass cylinder containing a 
hollow roll of amalgamated zinc. Within the 
zinc is a porous earthenware cell, in which is 
placed a small strip of platinum. The platinum, 
being so very costly, is placed on the inside for 
economical purposes. The outer cell contains 
dilute sulphuric acid, and the inner cell concen- 
trated nitric acid. When connection is made 



100 ELECTRICITY AND ITS DISCOVERERS. 

between the metals, the sulphuric acid, as usual, 
attacks the zinc, forming the sulphate of that 
metal, and the free hydrogen passes, by convec- 
tion, through the porous cell, and decomposes an 
equivalent of nitric acid, which readily yields up 
its oxygen to the hydrogen ; the deutoxide of 
nitrogen then rises to the surface of the fluid, 
and takes two equivalents of oxygen from the 
air, forming nitrous acid, which escapes in the 
form of red fumes. 

Though eminently energetic, this battery is 
very expensive, very difficult of management, 
and unhealthy, owing to the poisonous properties 
of the escaping nitrous acid. 

Bunsen's battery is composed of an outer cell 
of carbon, prepared from pulverized coal and 
coke, about ten inches in height and five inches 
in diameter. A porous cell of earthenware, con- 
taining a solid cylinder of amalgamated zinc, is 
placed within the carbon cell. Connection is 
made with the carbon cell, by running a wire 
around on its outside. Dilute sulphuric acid is 
poured into the cell having the zinc, and strong 
nitric acid into the carbon one. The carbon 
takes the place of the platinum in Grove's, and 
acts the part of the negative element or positive 



GALVAOTC BATTERIES. 101 

pole. This is an intensely powerful battery, and 
has the advantage of cheapness. It can not, how- 
ever, compete with Grove's, being unsteady in its 
work, owing, perhaps, to the earthy matter found 
in the carbon, and rendering it a bad conductor. 

The chromic acid and Marie-Davy batteries 
are modifications of the Bunsen battery. In the 
former, the nitric acid is replaced by a mixture 
of bichromate of potash and sulphuric acid ; and 
in the latter the zinc stands in water, and proto- 
sulphate of mercury is substituted for the nitric 
acid. 

The unit of the electro-motive force of a bat- 
tery is called a volt, and is about seven per cent 
less than a single Daniell's cell. The unit of re- 
sistance is called an ohm, and is about four hun- 
dred and six feet of the ordinary telegraph wire, 
known as number eight. The unit of the strength 
of a current is called a farad, and 1b the amount 
of electricity that flows, in the space of a second, 
from a cell whose electro-motive force is a volt, 
through a wire whose resistance is an ohm. 

The relative electro-motive forces of the prin- 
cipal batteries are as follows : Grove's, 1*92 ; Bun- 
sen's, 1-88; Daniell's, 1*079; and Smee's, 0*47. 

When points of prepared carbon are attached 



102 ELECTRICITY AND ITS DISCOVERERS. 

to the ends of the wires connecting the poles of 
a powerful galvanic battery, and then brought 
together, intense heat and light are instantly pro- 
duced. It is necessary, however, to join the 
points, before the phenomena of heat and light 
are perceptible. Once the connection is made, 
the points may then be withdrawn to a short 
distance, and the flame will still continue, form- 
ing itself into the shape of an arch, much broader 
at the negative than the positive pole. The car- 
bon of the positive pole consumes much more 
rapidly than that of the negative, particles of the 
carbon being carried from one pole and deposited 
on the other. If a very powerful Grove or Bun- 
sen battery be employed, the arch may be length- 
ened out some inches. The galvanic circuit pro- 
duces the most intense heat in nature this side 
the sun, and the light is the most brilliant artifi- 
cial light known. The most refractory metals 
yield to this heat, steel and platinum readily fus- 
ing, and even undergoing volatilization, when sub- 
jected to its influence. By combining several 
hundred Grove or Bunsen cells, the diamond 
may be volatilized. The galvanic light resembles 
very closely the light of the sun, and can be 
used for photographic purposes. This light is 



GALVANIC BATTERIES. 103 

not the effect of combustion, for it may be pro- 
duced in a vacuum, under water, or in a gaseous 
atmosphere that does not support combustion. 

As the carbon points gradually wear away, and 
thus increase their distance apart, the light, after 
a short space, suddenly goes out. To obviate 
this, and render the flame continuous, an in- 
genious piece of mechanism is used to move the 
points forward in proportion to their exhaustion, 
and so hold them regularly at the one distance. 

Each of the metals, when deflagrated by the 
galvanic current, has its own peculiar color. 
Gold burns with a vivid white light, silver with 
an emerald green, copper and tin with a pale 
bluish, lead with a purple, and zinc with brilliant 
white. 



CHAPTER IX. 

ELECTRO-CHEMICAL DECOMPOSITION, ELECTROTYPING, 
AND GILDING. 

The galvanic current has been of the greatest 
use in chemistry, in decomposing compound bod- 
ies into their elementary constituents. It was by 
this means that Davy reduced the metals potas- 
sium, sodium, calcium, magnesium, and others 
from their alkalies, potash, soda, lime, and mag- 
nesia. If the wire that completes a galvanic 
circuit be parted in the middle, and the ends 
tipped with platinum, and then introduced into 
a vessel of water, oxygen gas will bubble up at 
the positive end, and hydrogen at the negative. 
The water is decomposed into its elements of 
oxygen and hydrogen. If graduated glass tubes, 
filled with water, be let down over the ends of 
the wire, oxygen will rise in one end, and hydro- 
gen in the other, expelling the water. 

Twice as much hydrogen as oxygen, by vol- 



ELECTRO-CHEMICAL DECOMPOSITION, ETC. 105 

ume, should be given off in the same time, be- 
cause water is composed of two measures of 
hydrogen to one of oxygen. In actual experi- 
ment, however, it is found that a little more 
than twice as much hydrogen as oxygen is given 
off, because oxygen, being soluble in water, 
loses some little in being dissolved by the 
water. 

It seems that the positive wire decomposes an 
atom of water, the oxygen escaping into the air, 
producing a bubble; the hydrogen is at the 
same time set free and polarized, and attacks the 
neighboring atom of water, taking its oxygen, 
forming water, and setting hydrogen free, which, 
being polarized, attacks the next atom of water, 
and so on, until the last atom of hydrogen 
escapes at the negative wire, also producing a 
bubble. If copper, or other oxidizable metal, had 
been the terminus of the positive wire, instead 
of platinum, the oxygen would have united with 
such metal, forming its oxide, and thus prevent- 
ing the oxygen from being given off. A great 
many other substances besides water are decom- 
posed in this way. 

Dr. Faraday, to whom this branch of the sci- 
ence of electricity is greatly indebted, has intro- 



106 ELECTRICITY AND ITS DISCOVERERS. 

duced some Greek terms, which, being widely- 
used, need some explanation. 

This manner of decomposition is itself called 
electrolysis, from electron, signifying electricity, 
and luein, to loose or dissolve. The substances 
to be decomposed are called the electrolytes, from 
electron, as before, and lutos, dissoluble. The ends 
of the wire are said to be the doors through 
which the electricity flows, and hence are called 
electrodes, the Greek hodos meaning a way or 
path. The elements of the decomposition are 
called ions, from the Greek participle ion, going, 
from the fact of these elements going to the posi- 
tive or negative electrode. The electrodes are 
also called the anode and cathode, the positive 
being the anode, from ana, upward, and hodos, 
way, or the upward way, or the way the sun rises ; 
and kata, downward, and hodos, way, or downward 
way of the sun. 

The galvanic current does not decompose bod- 
ies in the solid state; it is necessary that the 
electrolyte, in order to suffer decomposition, be 
reduced to the liquid state either by solution or 
fusion. For instance, the chlorides of lead, sil- 
ver, and tin must be fused, in order to become 
fit subjects for the decomposing influence of the 



ELECTRO-CHEMICAL DECOMPOSITION, ETC. 107 

galvanic current. Some liquid compounds also 
are unaffected by the current, refusing to conduct 
it, such as a solution of ammonia; some others 
conduct the current well enough, and still are 
not decomposed by it, as, for example, sulphuric 
acid. 

When compound solutions are submitted to 
the influence of the current, the electro-negative 
elements invariably go to the positive electrode, 
and the electro-positive go to the negative elec- 
trode. In the electrolysis of muriatic acid, sul- 
phate of copper, nitrate of lead, chloride of sodi- 
um, or iodide of potassium, the iodine, chlorine, 
sulphuric and nitric acid, are set free at the posi- 
tive electrode ; and soda, potash, hydrogen, cop- 
per, and lead, at the negative. 

All bodies have what are called equivalents, 
or atomic weights, that is, the proportionate weight 
in which they unite with other bodies. All bod- 
ies will suffer a decomposition, by the same 
strength of current in any given time, proportion- 
ate in amount to their atomic weight. For in- 
stance, a galvanic current, sufficient to decompose 
9*01 grains of water, will in the same time de- 
compose 58*78 grains of chloride of sodium, 163*28 
of sugar of lead, 79'SS of blue vitriol. 



108 ELECTRICITY AND ITS DISCOVERERS. 

The amount of decomposition is always di- 
rectly proportioned to the quantity of electricity 
that passes through the electrodes, and hence elec- 
trolysis is a true measure of electricity. 

A great deal of galvanic action is often wasted 
on electrolytes that are poor conductors, as they 
impede the progress of the current. The addition 
of a liquid that is a good conductor sometimes 
greatly facilitates the work of the current. Water 
is a poor conductor, and the passage of a current 
through it is usually slow, but if a little sulphuric 
acid be added, the decomposition of the water 
becomes much more rapid, and the current util- 
ized to its utmost. In decomposing water, if, in- 
stead of collecting the gases in separate tubes, 
they be collected into a single receiver, and an 
electric spark passed through them, they will ex- 
plode, forming water. It is found that the quan- 
tity of electricity generated by the decomposition 
of a single grain of water will be just sufficient 
to recombine an amount of oxygen and hydrogen 
to form one grain of water, or, there is an exact 
correlation between these forces. 

Electrotyping is the process of depositing upon 
any surface a coating of metal from one of its 
metallic solutions by means of a galvanic current. 



ELECTEO-CHEMICAL DECOMPOSITION, ETC. 109 

Copies of the most delicate medals or engravings 
can be thus produced in gold, platinum, silver, 
copper, zinc, tin, lead, cobalt, nickel, brass, or 
bronze. Even the delicate tracings of Daguerre's 
exquisite pictures can be perfectly copied by this 
method. Every line, and even the shades of pol- 
ish of an engraving, may be accurately repro- 
duced. 

In considering the action of a Daniell's cell, 
it was noticed that the sulphate of copper was 
decomposed through the agency of the current, 
and metallic copper precipitated on the copper 
plate. The copper plate of the battery is thus 
covered with a film of bright, crystalline, malleable 
copper, which may be easily removed. This film 
is found to be an exact fac-simile of the copper, 
every tiniest scratch being copied. It was this 
observation that led to electrotyping. 

If the wires from the poles of a Smee's bat- 
tery be immersed in a vessel containing a solu- 
tion of sulphate of copper, the copper will go to 
the negative electrode, and the acid to the posi- 
tive one. If a copper cast of a medal or engrav- 
ing is sought, the model is suspended in the so- 
lution from the negative electrode, while the posi- 
tive electrode is simply immersed in the solution. 



110 ELECTRICITY AND ITS DISCOVERERS. 

All parts of the model not desired to be copied 
are covered with a resinous varnish, or some simi- 
lar non-conductor. If the surface to be copied, 
such as a cast of wax or sulphur, be a non-con- 
ductor, it may be made a conductor by a thin 
layer of powdered plumbago. The thickness of 
the film, or coating, is proportioned to the length 
of time the battery is operating. Thus, the elec- 
trotype can be made as thick or as thin as re- 
quired. 

In this way copper electrotypes are taken of 
the map-plates of the Coast Survey of the United 
States, saving an immense amount of expense, 
and preserving the original plate. The original 
plate is never printed on, as a few hundred im- 
pressions on paper would be sufficient to render 
it useless, by obliterating the delicate lines of the 
engraving. The first impression or the first elec- 
trotype copy is in relief, and, to obtain an exact 
fac-simile, the electrotype must itself be electro- 
typed. 

If, instead of sulphate of copper, a solution 
of chloride of gold be placed in a glass vessel, 
or earthenware trough, and the wires of a Smee's 
battery introduced, the gold will go to the nega- 
tive electrode, and the chlorine to the positive. 



ELECTRO-CHEMICAL DECOMPOSITION, ETC. HI 

In this way the baser metals may be covered or 
tinted with the precious, in a permanent and per- 
fect manner. A coating of gold, thinner than the 
thinnest gold-leaf, can be laid on by this pro- 
cess, or, if desired, may be made several inches 
in thickness. The surface to be gilt must be 
suspended from the negative electrode, being first 
cleaned with great care, in order that the gold 
may adhere. 

If, instead of chloride of gold, the trough con- 
tains a weak solution of cyanide of silver in 
cyanide of potassium, surfaces may be plated 
with silver. It is necessary to first clean the 
surface with warm caustic potash, and then wash 
it with nitrate of mercury. The nitrate of mer- 
cury leaves a thin film of mercury behind it on 
the surface, and this acts as a cement between 
the article and the silver. The thickness of the 
silver plating will depend on the length of time 
of immersion. In this process of plating, a piece 
of silver is attached to the positive electrode, 
and the article to be plated to the negative. 
During the action, the silver of the cyanide is 
deposited on the article fixed to the negative 
electrode, while the cyanogen passes, by convec 
tion, to the positive electrode, where it attacks the 



112 ELECTRICITY AKD ITS DISCOVERERS. 

silver there suspended, and forms with it cyanide 
of silver, thus dissolving the silver, and keeping 
up the saturation. In this way a piece of silver 
of any shape or form may be converted by the 
galvanic current into a uniform plate or covering. 









V 




CHAPTEK X. 



GALVANI AND VOLTA. 



Luigi Galvani, who has given his name to 
the electricity of chemical action, was a famous 
physicist of Bologna, where he was born on the 
9th of September, 1737. Galvani followed the 
profession of medicine, in which he attained to 
eminence. He studied under the renowned mas- 
ters Beccaria, Tacconi, and Galeazzi. He was 
very devout, especially in his youth, and early 
resolved to study for the Church, but friends 
dissuaded him from the step. 

Galvani was elected Professor of Anatomy in 
the Institute of Bologna in 1762. Here his 
lectures were remarkable for their clearness and 
accuracy, and he won great popularity. He also 
wrote several scientific works, the chief of which 
are "Considerations on the Urinary Organs, 55 
and "On the Organs of Hearing of Birds. 55 



114 ELECTRICITY AND ITS DISCOVERERS. 

Galvani, however, is indebted to his wife for 
the immense celebrity his name has reached. 
She was the daughter of the eminent medical 
professor Galeazzi, and was a woman of superior 
mind and vast attainments. She was the real dis- 
coverer of galvanism, and is, indeed, the mother 
of the modern science of dynamic electricity. 

"While preparing frog-legs, she noticed that 
they became wonderfully convulsed when placed, 
by accident, on a scalpel in contact with a charged 
electric machine. She informed Galvani of her 
discovery, who forthwith began a series of experi- 
ments in electricity, which he continued through 
many years, inspiring thereby others, and particu- 
larly Yolta, to pursue with ardor this science 
under its new form. As a consequence, the 
science of electro-dynamics gradually grew and 
developed. 

In some of his later experiments, Galvani pro- 
duced the convulsions and twitchings of the frog- 
legs, without the aid o? electricity, by simply 
touching the nerves with one metal, and the 
muscles with a different one, and joining the 
metals. Galvani insisted that the electricity re- 
sided in the limbs, the metals merely acting as 
conductors of the fluid. 



GALVANI AND VOLTA. 115 

Volta, on the contrary, argued that the elec- 
tric excitement was owing to the simple contact 
of dissimilar metals. They were both but partly 
right, as it is now generally conceded that the 
current is generated principally by chemical ac- 
tion. 

Galvani's views on electricity are contained in 
his principal work, which is a commentary, "De 
Viribus Electricitatis in Motu llusculari." Gal- 
vani died in his sixty-first year. 

One of the most illustrious electricians of all 
time was Alessandro Volta, a native of Como, 
and born in 1745. In 1774 he reached the chair 
of Physics at Pavia. His labors in electricity 
were truly indefatigable. Starting from the crude 
experiments of Galvani on the frog-legs, he gradu- 
ally advanced to the construction of his "pile," 
which is a complete and perfect galvanic battery. 
It is said to be the greatest invention of a single 
mind the world ever saw. 

He was invited by Napoleon Bonaparte to 
Paris, to exhibit the working of his "pile" to 
the French Institute. Napoleon enrolled him in 
the Legion of Honor, conferred upon him the 
order of the Iron Crown, and the titles of Count 
and Senator of the Kingdom of Italy. 



116 ELECTRICITY AND ITS DISCOVERERS. 

Volta, in opposition to Galvani, maintained 
the contact theory, as it is called. He believed 
that the galvanic current owes its origin to the 
simple contact of dissimilar metals, ignoring both 
the animal theory of Galvani, as also that of 
chemical action. 

Volta was the inventor of the electrophorus, 
the electrical condenser, the hydrogen-lamp, the 
electrical pistol, and the eudiometer, for testing 
the purity of the air. 

Volta was the recipient of distinguished honors 
from his own and other countries, and departed 
this life in his eighty-first year. 



CHAPTEK XL 

ELECTRO-MAGNETISM. 

Professor Oersted, of Copenhagen, is the 
father of the science of electro-magnetism. Al- 
though he had, for twenty years, suspected the 
relation between magnetism and electricity, it 
was not until 1819 that he discovered the law 
governing electro-magnetic attraction and repul- 
sion, and then fell upon it by the merest acci- 
dent. 

When a wire bearing a galvanic current is 
extended in a direction parallel with the mag- 
netic needle, but in the plane above it, the north 
end of the needle will be deflected to either side 
of the magnetic meridian, depending on the 
course of the current. If the current's direction 
is from north to south, the north pole of the 
needle will be driven toward the east ; if this 
direction is from south to north, the needle's 



118 ELEOTEICITY AND ITS DISCOVERERS. 

north pole will vibrate to the west, the degree 
of deflection depending on the proximity and 
strength of the current. 

If, instead of running along in the plane 
above the needle, the wire be placed in the 
plane beneath it, the reverse of the above takes 
place: the current entering from the north sends 
the needle's north end westward ; and coming in 
from the south, the north of the needle is driven 
eastward. 

Ampere has left an easy formula, by which 
the direction is always remembered : Let any 
one suppose himself to be lying in the direction 
of the positive current, his head representing the 
copper, and his feet the zinc, and looking at the 
needle, its north pole will always move toward 
the right hand. 

If a conducting wire be bent into the shape 
of a rectangle, and the needle placed between its 
horizontal branches, by referring to Ampere's 
formula it will be seen that the top and bottom 
currents tend to deflect the needle in the same 
direction, thus giving a double force to this 
tendency. By multiplying the folds of the wire, 
a most sensitive means of detecting the presence 
of an electric current has been devised, by the 



ELECTRO-MAGNETISM. 119 

ingenuity of Schweigger. Schweigger's instru- 
ment, improved by Chevalier Nobili, has been 
already described as the astatic galvanometer. 
The influence of the current on the needle di- 
minishes inversely as the square of their mutual 
distances, for very short wires; but, when the 
wire's length is considered infinite, the intensity 
of its attraction is simply in the inverse ratio of 
the distance. 

The third law of motion is, that when one 
body acts upon another, action and reaction are 
equal and in opposite directions. If the mag- 
netic needle had been stationary, in the above 
instances, and the wire free to move, the move- 
ments of the wire, in virtue of this third law of 
motion, would be, by reaction, in strict accord- 
ance with the principles governing the conduct 
of the needle. 

"Wires conducting galvanic currents moving in 
the same direction, attract one another; and in 
opposite directions, repel. 

Experiment has fully proved that the force 
by which the electric current acts on the mag- 
net is neither that of attraction nor repulsion, 
but tangential, its tendency being to cause the 
poles of the magnet to revolve about the wire in 



120 ELECTEICITY AND ITS DISCOVERERS. 

opposite directions, until a state of equilibrium is 
reached, where the action of one pole just bal- 
ances that of the other. Taking advantage of 
this principle, Dr. Faraday, by ingeniously con- 
triving to confine the action of the current to 
one pole, was enabled to produce a rotary motion 
of the magnet. 

If a bar of soft iron be inserted in a spiral- 
shaped coil of wire, and the two ends of the 
wire connected with the poles of a galvanic bat- 
tery, the bar will be instantly converted into a 
magnet, but will lose its magnetism when the 
circuit is broken. If, instead of soft iron, a 
piece of steel be used, the magnetism acquired 
will be permanent. In this spiral coil, commonly 
called a helix, the wire should be covered with a 
wrapping of silk, or very fine cotton thread, to 
prevent the spirals from attracting one another, 
and drawing so closely together that there is 
danger of the current flashing from one end to 
the other, without passing around the whole coil. 

The position of the poles in this temporary 
or electro-magnet depends on the direction of the 
current. If the soft-iron bar in the helix stands 
north and south, and a current from the copper 
plate of a battery be passed around it from north 



ELECTRO-MAGNETISM. 121 

to south, in a direction opposite to the apparent 
motion of the sun, the north end of the bar will 
be a north pole and the south end a south pole, 
as may be perceived by its attracting the opposite 
poles of a magnetized needle. But, if the passage 
of the current corresponds with the sun's apparent 
path, the south end will be the north pole, and the 
north end the south pole of the bar. 

The helix, during the passage of the current, 
assumes magnetic properties, and, if freely sus- 
pended, will place itself in the direction of the 
magnetic meridian. In this position it will pre- 
sent all the properties of a magnetized needle, 
being attracted by the opposite, and repelled by 
the same pole of a magnet. 

If a fine needle be inserted in the helix, it 
will be equally attracted by all parts of the spiral 
at the same time, and so place itself unsupported 
in the center of the helix, like Mohammed's fa- 
bled coffin. 

The iron bar should be so placed in the helix 
that its axis will be at right angles to the direc- 
tion of the current. The farther the bar is re- 
moved from this position, the more its magnetic 
intensity diminishes. 

Electro-magnets may be made far more power- 



122 ELECTRICITY AND ITS DISCOVERERS. 

f ul than any natural magnets. The intensity of an 
electro-magnet is, in a great measure, determined 
by the strength of the current, and the number 
of the convolutions in the helix. When the iron 
core of the helix is very thin, there is a limit to 
the number of convolutions, beyond which no in- 
crease in magnetic force is gained. The greater 
the number of folds, the greater the resistance 
offered to the passage of the current. So that 
there is a fixed relation between the number of 
convolutions and the strength of the current, 
that should not be deviated from, in order to 
secure the maximum magnetic intensity. The 
maximum of magnetic force in different magnets 
is proportioned to the area of section, or to the 
square of the diameter of the core. 

The usual form of the electro-magnet is still 
called the horseshoe, although it has departed quite 
considerably from the horseshoe-shape. It con- 
sists of a flat rectangular base of soft iron down 
into which are screwed two cylindrical soft-iron 
rods, one near each end of the base, and not ex- 
ceeding four inches in length. Thick helices of 
insulated copper wire are put down over these 
uprights. The wire is coiled in the helices in 
the same manner as if there had been but one 



ELECTRO-MAGNETISM. 123 

straight, continuous bar. An armature of very soft 
iron is placed over the poles of this magnet. 
The softer the iron of the armature the better, 
that the magnetism may instantly vanish, on the 
breaking of the circuit. A magnet of this kind, 
with a powerful battery attachment, may be made 
to sustain thirty-five hundred times its own weight, 
or a matter of several tons. 

The celerity with which the soft iron becomes 
magnetic, on closing the circuit, and loses its 
magnetism on breaking it, has been utilized to 
produce, automatically, extremely rapid motion. 
As an instance of this automatic action, suppose 
one plate of a battery to be connected with the 
wire forming the helix of an electro-magnet, and 
thence connected with a brass upright. To this 
brass upright is fastened a horizontal metallic 
spring, which holds up the armature of the elec- 
tro-magnet with sufficient force, when the circuit 
is open, to press it against an adjustable screw 
joined by wire to the other pole of the battery. 
The passage of the current magnetizes the elec- 
tro-magnet, which draws down the armature from 
its contact with the screw, and thus severs its 
connection with one pole of the battery, breaking 
the circuit. The electro-magnet loses its magnet- 



124 ELECTRICITY AND ITS DISCOVERERS. 

ism, the circuit being broken, and ceases to at- 
tract the armature, which is then thrown up, by 
the action of the spring, against the screw, again 
closing the circuit, and magnetizing the electro- 
magnet, which draws down the armature, break- 
ing the connection, and so on, producing of its 
own accord a continuous and most rapid mo- 
tion. 

Dr. Faraday observed, in 1830, that a galvanic 
current traversing a wire will induce a moment- 
ary current in another wire lying alongside of 
it. This second wire is not connected with a 
battery, but should form a closed circuit. The 
induced or secondary current, as it is called, is 
in an opposite direction to the primary ; it is 
merely a throb, that ceases instantly on the clos- 
ing of the primary circuit. As long as the first 
current continues to flow, this secondary one gives 
no evidence of its existence ; but, on the break- 
ing of the primary current, the induced or sec- 
ondary again appears, but only momentarily, and 
in the same direction as the primary. There 
are, then, two induced currents : one, on making 
the connection between the poles of a galvanic bat- 
tery ; and one, on breaking the connection. The 
current induced by closing the primary circuit is 



ELECTRO-MAGNETISM. 125 

in a direction opposite to the primary, but the 
one induced by opening the primary is in the 
same direction as the primary. 

It is found that the longer the wires of both 
primary and secondary circuits, within certain lim- 
its, the greater the strength of the induced cur- 
rent and the severer the shock it imparts. Ad- 
vantage has been taken of this to construct elec- 
tric machines to communicate shocks for medici- 
nal and other purposes. One coil of wire is placed 
within another coil ; the ends of the inner coil 
are connected with the poles of a galvanic battery, 
and the ends of the outer coil are held by the 
person to whom it is desired to impart the shock. 
As often as the circuit is closed or opened in the 
inner helix, an induced current is generated in 
the outer helix, which communicates a shock to 
the person in contact with its poles. In order to 
produce the shocks with sufficient rapidity, an 
automatic circuit-breaker, as already described, is 
attached to the battery circuit. 

The induced current has the ordinary proper- 
ties of the galvanic current, and has, moreover, 
great tension like static electricity. 

It has been stated that so long as the primary 
current continues to flow there is not the least 



126 ELECTRICITY AND ITS DISCOVERERS. 

sign of electric excitement in the second wire 
after the first throb ; but if the second wire is 
moved towards the wire conveying the current, 
an induced current is generated in the second 
wire, in a direction opposite to the primary cur- 
rent. If, instead of the second wire being moved 
toward the first, it be moved away from it, a 
secondary current is induced in the second wire, 
in the same direction as the primary current. 

It is not necessary, for the purposes of induc- 
tion, that the second coil should surround the first ; 
it may only be laid upon it or above it. Nor is 
the effect confined to the second coil ; but, if a 
third or fourth coil be connected with the second, 
currents of electricity will also be induced in them 
at each interruption of the battery-current. The 
currents in the several coils move in different di- 
rections. 

When the battery circuit is closed, a current 
in the second coil moves in the opposite direction, 
called the initial current ; and, when it is opened, 
the secondary current flows in the same direction, 
and is called the terminal current. The initial 
current will induce a tertiary current flowing in 
the opposite direction ; and the terminal current, 
a tertiary current flowing also in an opposite di- 



ELECTRO-MAGNETISM. 127 

rection. These tertiary currents can induce cur- 
rents in other helices of a fourth and even the 
seventh order. 

In the very same wire in which the current 
is traveling an induced current is produced, on 
closing the circuit, when the wire is coiled into a 
helix. This current induced in the same wire is 
called the extra current, and is in the opposite 
direction to the main current, and so impedes 
its passage and lessens its power. On breaking 
the circuit, an extra current is again induced, 
though in the same direction as the original cur- 
rent, thus adding to its strength. This is the 
reason why a greater shock is experienced, by a 
person holding the poles of an induction battery, 
at the breaking than at the closing of a circuit. 
Because of this extra current, the magnetism of 
an electro-magnet does not instantly vanish on 
the breaking of a circuit. It is thus owing to 
the existence of this extra current that the speed 
of an electro-magnetic motor can not be increased 
beyond a certain limit, and so can not be employed 
to any great advantage in mechanics. 

The longer the wire, the greater the duration 
of the extra current, sometimes reaching as much 
as three quarters of a second, and hence telegrams 



128 ELECTRICITY AND ITS DISCOVERERS. 

can be sent far more rapidly along a short circuit 
than a long one. 

The ease and celerity with which the electro- 
magnet takes up and lays down its magnetism 
renders it of supreme importance to telegraphy. 



CHAPTER XII. 



OERSTED AND AMPERE. 



Hans Christian Oersted, the father of electro- 
magnetism, and a scientific discoverer of great 
fame, was a native of Denmark, and born in 1777. 
He won the degree of Doctor of Philosophy from 
the University of Copenhagen, in 1799, and im- 
mediately after began the profession of medicine. 

In 1806 he was appointed to the chair of 
Natural Philosophy in the University of Copen- 
hagen. His fame as a physicist, especially in the 
department of electricity, soon spread over Europe. 
His main efforts in science were directed toward 
proving the identity of magnetism, electricity, and 
galvanism. It was while engaged in experiments 
toward this end that he made his greatest dis- 
covery, that of electro-magnetism, the chief pillar 
of his reputation, and, in fact, one of the very 
greatest discoveries ever made in physical science. 



130 ELECTRICITY AND ITS DISCOVERERS. 

Many honors were bestowed on Oersted for 
his brilliant discoveries. He was corresponding 
member of the French Institute, perpetual secre- 
tary to the Royal Society of Sciences in Copen- 
hagen, a knight of the Order of Merit in Prussia, 
of the Legion of Honor in France, of the Danish 
Order of the Dannebrog, and a councilor of state. 

Oersted was much honored by his country, both 
before and after his death, for it was apparent that 
his chief aim in life was to contribute to the im- 
provement and well-being of his fellow-citizens. 

Andre Marie Ampere, "the intellectual Am- 
pere," as Humboldt named him, was born at Lyons, 
January 20, 1775. A shadow was thrown over his 
whole life by his fathers tragic death, beneath the 
blade of the guillotine, in the Revolution of 1793. 

Ampere was a very great mathematician and 
a most distinguished scientist. He was elected 
member of the Academy of Sciences in 1814, and 
in 1824 was appointed to the chair of Experimental 
Physics in the College de France. He labored 
hard to show the identity of magnetism and elec- 
tricity, and his theory of electro-dynamics reached 
great fame. 

Although Oersted was the discoverer of electro- 
magnetism. Ampere was the great expounder of 



OERSTED AND AMPERE. 131 

its laws. He was the author of the celebrated 
formula for determining the movements of the 
magnetized needle under the influence of the gal- 
vanic current. 

Ampere contributed very valuable aid toward 
all the departments of electricity. He w r as an ori- 
ginal thinker of great versatility, and an inde- 
fatigable laborer in the fields of electro-dynamics. 

What was most admirable in Ampere was his 
disinterested love of science, which made him take 
almost as much interest in the discoveries and 
labors of other men as in his own. 

He was a devoted Christian, and fulfilled all 
his religious obligations with fervor and simplicity. 
His distinguished son, after enumerating his claims 
to imperishable fame, ends with these words : " A 
true Christian, he loved humanity. He was good, 
simple, and great.'" 



CHAPTER XIII. 

THE ELECTRIC TELEGRAPH. 

The positive and negative electricities of a 
galvanic battery have a wonderful tendency to 
unite, and, when the opposite poles are joined by 
a conducting wire, these fluids flow together with 
inconceivable rapidity. It matters not how long 
this wire may be ; provided it is a good conductor, 
they will traverse it with the same winged speed. 
Advantage has been taken of this attraction be- 
tween the fluids, their great velocity, and the dis- 
covery of the electro-magnet, to devise a means of 
quick intelligence between distant stations. 

The telegraph, from the Greek tele, far, and 
graphein, to write, is the medium of this communi- 
cation. If the wire from the positive pole of a 
battery ran completely around the globe to join its 
negative pole, the current would travel the circuit 
in one second, were the wire's conductivity per- 
fect. 



THE ELECTRIC TELEGRAPH. 133 

When it is desired to send a signal to a dis- 
tant station by means of the battery, the metallic 
circuit connecting the poles must reach there and 
back; a continuous wire must run from the posi- 
tive pole to the station, and from the station back 
to the negative pole. The fluid will then pass over 
this distance and back, from one pole to the other, 
forming a complete circuit. 

The principle of telegraphic signaling is quite 
simple. The wire from the positive pole of a 
battery is borne along over insulated supports to 
the distant station, where it is joined to the helix 
of an electro-magnet, and similarly borne back 
again to the negative pole of the battery, thus 
completing the circuit. 

Since the celebrated discovery of Professor 
Steinheil, however, in 1838, that the earth is a 
perfect conductor, one of the wires has been dis- 
pensed with, the earth taking the place of the 
returning wire. To complete the circuit, under 
this consideration, the wire from the copper plate 
of a battery is extended on insulators to the dis- 
tant station, there joined to the helix of an electro- 
magnet, and thence connected with a large copper 
plate sunk in the earth. The zinc element of the 
battery is in like manner joined by wire to a large 



134 ELECTRICITY AND ITS DISCOVERERS. 

copper plate, also sunk in the earth. It will be 
readily seen that there is thus a complete circuit 
between the copper and zinc elements of the bat- 
tery, through the medium of the earth and the 
single wire. The positive electricity runs along 
the wire to the helix of the distant station, and 
thence, by way of the sunken copper plate, into 
the ground, and, by way of the earth, back to the 
sunken copper attached to the zinc, through which 
it reaches the zinc, thus completing the circuit. 

Over the electro-magnet, at the distant station, 
is placed an armature attached to a lever moving 
vertically on a horizontal pivot, so that, when the 
armature is drawn down by the attraction of the 
electro-magnet, the opposite end of the lever is 
thrown up against a wooden roller. When the 
electro-magnet becomes demagnetized by the break- 
ing of the current, it ceases to hold down the arma- 
ture. There is a spring attached to the armature 
to draw it up, when freed from the attraction of 
the electro-magnet. The end of the lever that 
presses against the roller has a steel point precisely 
fitting into a delicate groove in the roller. Over 
this roller is carried a narrow paper tape in a reg- 
ular and continuous manner, by means of clock- 
work. 



THE ELECTRIC TELEGRAPH. J 35 

At the sending-station there is a key inserted 
in the circuity by which the current can be opened 
or closed at the pleasure of the operator. The key 
is a simple spring, which is pressed down by the 
operator's finger to complete the circuit, by estab- 
lishing metallic communication between the poles 
of the battery. 

When the sender presses down his key, he com- 
pletes the circuit, the current passes over the wire 
to the distant station, magnetizes the electro-mag- 
net, draws down the armature, and throws up the 
steel point against the paper tape passing along the 
roller. The steel point indents the paper tape, by 
pressing it into the groove upon this roller. So 
long as the current passes, the steel point presses 
the paper, making a continuous mark. As soon as 
the circuit is broken, the electro-magnet discharges 
its magnetism, and the steel point falls away from 
the paper and ceases to mark. The circuit being 
renewed, the point marks again ; and this may be 
repeated as often as the operator pleases. The 
sender can break or close the circuit as often and 
as rapidly as he pleases, and it will be all recorded 
in proper shape at the receiving-station. The 
length of time that the circuit is closed will be 
exactly registered in the corresponding length of 



136 ELECTRICITY AND ITS DISCOVERERS. 

the mark made by the steel point. A touch will 
produce a dot, a continued pressure a long line, and 
intermittent repeated touches a series of dots and 
short lines. These easily form an alphabet. To 
complete the arrangement, the operator at each 
station must have his own key, as well as electro- 
magnet. The clock arrangement is so contrived 
that the attraction of the armature by the electro- 
magnet, on the first closing of the circuit, sets it 
in motion. 

The telegraphist's alphabet is the offspring of 
a conventional arrangement of dots and dashes. 
The Morse system of telegraphy is superior to all 
others, its method of notation being by far the 
simplest and most complete. 

The following are the Morse characters: 

A O-- 1 

B P 2 

C Q 3 

D R 4 

E- S 5 

F T 6 

G U 7 

H V 8 

I-- W 9 

J X 

K Y 

L Z 

M & 

N 



THE ELECTRIC TELEGRAPH. 137 

The wire connecting the stations should be as 
perfectly insulated as possible. It is the disposi- 
tion of the electric fluids to unite by the nearest 
route. If the wire, before reaching its destination, 
should accidentally come in contact with the earth, 
the current, instead of passing all the way around, 
would speed back to the battery by this shorter 
path. The wire is usually strung to cedar or chest- 
nut poles, by means of glass or porcelain connec- 
tions. The average number of poles to a mile is 
thirty. In climates of uniform temperature so 
many are not requisite ; but with us, owing to the 
great vicissitudes of heat and cold, there is often a 
variation of four feet per mile in the length of the 
wire, and the safety of the line calls for this number. 

As in practice it has been found utterly im- 
possible to perfectly insulate the wire, the strength 
of the current is continually ebbing away, pass- 
ing in little streams into the earth; as a conse- 
quence, messages are never sent beyond fifty or 
sixty miles without the assistance of a local bat- 
tery. Through the means of an electro-magnet, 
or relay, as it is called, the weak current of the 
main line opens or closes the current of the local 
battery, which then acts instead of the main cur- 
rent in working the receiver's armature. 



138 ELECTKIOITY AND ITS DISCOVERERS. 

The relay is simply an electro-magnet, which 
is placed in the main circuit, and performs the 
office of opening and closing the current of a 
local battery, at the receiving-station, which bat- 
tery in turn works the register or sounder. 

Some very limited telegraphic systems elimi- 
nate the earth connection, finding it more conven- 
ient to use a continuous metallic circuit, as, for 
instance, the municipal fire-alarm telegraph. 

Iron wire, about one eighth of an inch in 
diameter, and weighing from three to four hun- 
dred pounds per mile, is universally used for tele- 
graphic purposes. The wire is galvanized, to pre- 
serve it from oxidizing. The best wire is made 
from Swedish charcoal-iron. Copper is a better 
conductor than iron, in the proportion of six to 
one ; but iron is much cheaper. 

A switch is attached to every operator's key, 
to enable him to close the circuit when not 
working. When finished operating, he slides the 
switch in between the key and the wire, thus 
keeping the circuit constantly closed. This is 
called the closed-circuit plan, and is the one em- 
ployed on all American lines using the Morse 
method. 

The movement of the armature is confined 



THE ELECTKIG TELEGKAPH. 139 

within fixed limits by adjustable stops, and so 
regulated that the armature never altogether 
touches the electro-magnet. If the armature came 
into actual contact with the electro-magnet, it 
would not discharge its magnetism instantly on 
the breaking of the current, and so would impede 
the work of recording. 

The paper tape, or register, is no longer em- 
ployed in this country, except at very small sta- 
tions. In all the large offices, the operators are 
so expert that they can read the message by the 
sound of the armature, and can so dispense with 
the register. The language of the instrument is 
so familiar to their ears that they write the mes- 
sage without hesitancy, in the ordinary letters of 
the vernacular. To facilitate this method, there 
is attached to the instrument a sounder. The 
armature is made quite heavy, and is operated by 
a strong local battery and relay, to give the 
stroke more volume. An arch or bridge is also 
provided, on which the stroke of the armature 
takes effect. The message is read from the spaces 
between the strokes, with which the ear of the 
operator becomes perfectly familiarized. 

The studs of the key through which connec- 
tion is made or broken are platinum, in order 



140 ELEOTKIOITY AND ITS DISCOVERERS. 

that they may not be oxidized or fused by the 
current's passage. This key makes the connection 
in as perfect a manner as if the wires themselves 
were brought into actual contact. 

When the operator at one station wishes to 
transmit a message to another station, he removes 
his switch, breaking the current's flow. The ar- 
matures of the relays and sounders at both sta- 
tions then fall off from their magnets. By break- 
ing and closing the circuit so as to form the 
characters of the telegraphic alphabet, the arma- 
tures of his own and the distant sounder will re- 
spond to every movement of his key, and thus 
the message may be copied by the distant opera- 
tor from his sounder. As the transmitter's own 
sounder answers to the movements of his key, the 
receiver may, at any time, interrupt him, by 
opening his switch and breaking the current. 
The sender is instantly notified of this interrup- 
tion by the failure of his instrument to work. 

A number of way-stations may be worked by 
one main line, provided each has its own relay 
and local battery. Twenty-five is about the limit, 
however, that can be advantageously so worked. 

The battery used in telegraphy is, generally, 
some form of Daniell's. The gravity battery an- 



THE ELECTRIC TELEGRAPH. 141 

swers the purpose very well. Some telegraph 
companies are beginning to substitute induced 
electricity, instead of galvanism, for the working 
of their lines. 

Several messages may be sent simultaneously 
over the same wire, by the use of proper mech- 
anism. The best manner of quadruplex transmis- 
sion is the invention of Prescott and Edison. 
Quadruplex telegraphy is the sending of four dis- 
patches, two from each of two different stations, 
at the same time. The eminent electrician Pres- 
cott explains his system thus : " The distinguish- 
ing principle of this method consists in combin- 
ing together two distinct and unlike methods of 
single transmission, in such a manner that they 
may be carried on independently upon the same 
wire, and at the same time, without interfering 
with each other. One of these methods of single 
transmission is known as the double-current sys- 
tem, and the other is the single-current or open- 
circuit system. In the double-current system the 
battery remains constantly in connection with the 
line at the sending - station, its polarity being 
completely reversed at the beginning and at the 
end of every signal without breaking the circuit. 
The receiving relay is provided with a polarized 



142 ELECTRICITY AND ITS DISCOVERERS. 

or permanently magnetic armature, but has no 
adjusting spring, and its action depends solely 
upon the reversals of polarity upon the line, with- 
out reference to the strength of the current. In 
the single-current system, on the other hand, the 
transmission is effected by closing and breaking 
or increasing and decreasing the current, while 
the relay has a neutral or soft-iron armature, pro- 
vided with a retracting spring. In this system 
the action depends solely upon the strength of 
the current, its polarity being altogether a matter 
of indifference. It will, therefore, be apparent 
that, by making use of these two distinct qualities 
of the current, viz., polarity and strength, two 
sets of instruments may be operated at the same 
time on the same wire." 

The power of sending any number of mes- 
sages simultaneously on the same wire is only 
limited by the delicacy of the adjustments which 
each additional current would entail ; any number 
of armatures may be attached to the same main 
wire, each so constituted as to be influenced dif- 
ferently by the current's flow. 

There are other systems of telegraphy besides 
the Morse, but none so much in use. 

A complex form of type-printing telegraph 



THE ELECTRIC TELEGRAPH. 143 

was patented by Royal E. House, of Vermont, in 
1846. The Bain chemical telegraph, employing 
no electro-magnet, transmits its signals by the de- 
composition of chemically prepared paper. 

The needle telegraph, depending on the deflec- 
tion of a needle by the galvanic current, was in- 
vented by Baron Schilling in 1832. 

"Wheatstone's dial telegraph was invented in 
1839. 

David E. Hughes, of Kentucky, patented a type- 
printing apparatus in 1855. 

Phelps patented an electro-motor printing in- 
strument in 1875. 

Telegraphic intelligence may be sent under the 
ocean, as over the land, provided the conducting 
wire receives proper insulation. The best material 
for the purposes of insulation thus far devised is 
gutta-percha, though even it is far from being 
all that could be desired. Insulation is the most 
difficult problem to be solved in telegraphy, gutta- 
percha having some serious defects. It dries up 
and cracks in sandy soil. It rots in very damp 
soil. It is easily damaged by the careless handling 
of workmen. 

The first successful attempt to send the gal- 
vanic current under water was across the Hudson 



144 ELEOTEIOITY AND ITS D1SCOVEKERS. 

Kiver, between New York and Jersey City, in 
1848. The first attempt at submarine cable-laying 
was in 1850, under the English Channel, between 
Dover and Calais. This first-born cable had but 
a day's ephemeral life. The next effort, however, 
made the following year, between the same places, 
was a complete success. All the waters of the 
world are now so girdled with cables that all 
peoples are in instant communion, through the 
electric telegraph. 



CHAPTEK XIV. 



PROFESSOR MORSE. 



Samuel Festley Breese Morse, the inventor 
of the electric telegraph, one of the greatest men 
of this century, was born April 27, 1791, at Charles- 
town, Massachusetts. He entered Yale College 
when he was in his fifteenth year. During his 
college-life his fondness for painting amounted to 
a passion, and he excelled in chemistry and mathe- 
matics. The celebrated Benjamin Silliman was his 
Professor of Chemistry. 

Morse was graduated from Tale in his eight- 
eenth year. He went to England in 1811 to learn 
painting, and put himself under the tutorship of 
Benjamin West and Washington Allston, both 
eminent American artists resident in London. He 
applied himself also to sculpture, and, in the year 
following his arrival in England, received from 



146 ELECTEICITY AKD ITS DISCOVERERS. 

the hands of the Duke of Norfolk the gold medal, 
the prize offered by the Adelphi Society of Arts 
for the best single figure in sculpture. 

In 1815, his money being exhausted, he de- 
parted from England and returned to America. 
For several years he obtained a very precarious 
livelihood, by painting portraits in Boston, Charles- 
ton, and New York. He founded the National 
Academy of Design in 1825, and became its first 
president. In 1829 he again visited Europe, to 
perfect himself in his art. After three years he 
returned to New York in the packet-ship Sully. 
It was during this homeward voyage that he de- 
signed the electric telegraph. lie had, however, 
been previously for years a close student of elec- 
tricity, and frequently attended the lectures of 
Professor Dana on electro-magnetism at the Athe- 
naeum. 

The labors of Galvani and Yolta had furnished 
a constant flow of electricity, and Oersted had sup- 
plied the electro-magnet, and thus were the ele- 
ments ready at hand to be molded to the purposes 
of the telegraph. 

Before Morse left the Sully he had not only 
devised, but perfected, in all its parts, his plan of 
a telegraph. All that is claimed for Morse is, that 



PROFESSOR MORSE. 147 

he linked together the great discoveries of other 
men, and fitted them to the purposes of commerce. 
Still, in this alone he performed a wonderful task, 
requiring a colossal brain and indomitable perse- 
verance. Over thirty years after the invention of 
his first crude instrument, at a magnificent banquet 
given in his honor at Delmonico r s, Professor Morse, 
in alluding to his telegraph, said : " In 1835, ac- 
cording to the concurrent testimony of many wit- 
nesses, it lisped its first accents and automatically 
recorded them, a few blocks only distant from the 
spot from which I now address you. It was a 
feeble child indeed, ungainly in its dress, stam- 
mering in its speech; but it had then all the dis- 
tinctive features and characteristics of its present 
manhood. It found a friend — an efficient friend — 
in Mr. Alfred Vail, of New Jersey, who, with his 
father and brother, furnished the means to give the 
child a decent dress preparatory to its visit to the 
seat of government. These few facts suffice here 
to indicate the birth of the telegraph." 

This Alfred Vail did, indeed, give efficient aid 
to the new invention. He improved very materi- 
ally Morse's crude instrument, and supplied the 
telegraphic alphabet. Morse had also other valu- 
able helpers. 



148 ELECTRICITY AND ITS DISCOVERERS. 

During the latter years of his artist-life, Morse 
had a tremendous struggle for very subsistence. 
Portrait-painting was not a lucrative vocation at 
that time. An instance of his distress is told by 
one of his pupils, Colonel Strother. "I engaged 
to become," says the colonel, "Morse's pupil, and 
subsequently went to New York and found him in 
a room in University Place. He had three other 
pupils, and I soon found that our professor had 
very little patronage. I paid my fifty dollars ; that 
settled for one quarter's instruction. Morse was a 
faithful teacher, and took as much interest in our 
progress, more, indeed, than we did ourselves. But 
he was very poor. I remember that, when my 
second quarter's pay was due, my remittance from 
home did not come, as expected, and one day the 
professor came in, and said, courteously : 

" ■ Well, Strother, my boy, how are we off for 
money ? ' 

" ' Why, professor,' I answered, ' I am sorry to 
say I have been disappointed ; but I expect a re- 
mittance next week.' 

" 'Next week ! ' he repeated, sadly ; i I shall be 
dead by that time ! ' 

"'Dead, sir?' 

"'Yes, dead by starvation!' 



PROFESSOR MORSE. 149 

"I was distressed and astonished. I said hur- 
riedly, ' Would ten dollars be of any service ? ! 

"'Ten dollars would save my life; that is all 
that it would do.' 

"I paid the money, all that I had, and we 
dined together. It was a modest meal, but good, 
and after he had finished, he said : ' This is my 
first meal for twenty-four hours. Strother, don't 
be an artist. It means beggary. Your life de- 
pends upon people who know nothing of your art, 
and care nothing for you. A house-dog lives bet- 
ter, and the very sensitiveness that stimulates the 
artist to work, keeps him alive to suffering. ' " 

Morse's struggle to have his invention recog- 
nized in a material way by Congress was a long 
and severe one. His faith in his invention, and his 
invincible perseverance, shine forth with brightest 
luster. He was ridiculed and rebuffed term after 
term of Congress. Still he persevered, until finally 
his friends succeeded in obtaining for him an ap- 
propriation of thirty thousand dollars. It was the 
last bill passed in the session of 1842. Just pre- 
vious to the passage of the bill, Morse had given 
up all hope, and had withdrawn in despair. 

The following legend is taken from "Harper's 
Monthly " : " Morse made his preparations to re- 



150 ELECTRICITY AND ITS DISCOVERERS. 

turn to New York next day, and, retiring to rest, 
sank into a profound slumber, from which he did 
not awake until a late hour on the following morn- 
ing. But a short time after, while seated at the 
breakfast-table, the servant announced that a lady 
desired to see him. Upon entering the parlor he 
encountered Miss Annie Ellsworth, the daughter of 
the Commissioner of Patents, whose face was all 
aglow with pleasure. 

" i I have come to congratulate you,' she re- 
marked, as he entered the room, and approached 
to shake hands with her. 

" ' To congratulate me ! ' replied Mr. Morse, 
'and for what?' 

" i Why, upon the passage of your bill, to be 
sure!' she replied. 

'< ' You must surely be mistaken ; for I left at 
a late hour, and its fate seemed inevitable.' 

" ' Indeed, I am not mistaken,' she rejoined ; 
6 father remained until the close of the session, 
and your bill was the very last that was acted on, 
and I begged permission to convey to you the 
news. I am so happy that I am the first to tell 
you ! ' 

" The professor very heartily thanked her, and 
said : ( As a reward for being the first bearer of 



PROFESSOR MORSE. 151 

the news, yon shall send over the telegraph the 
first message it conveys.' 

" ' I will hold yon to yonr promise/ replied she. 
c Remember ! ' 

" i Remember ! ' responded Morse ; and they 
parted." 

In May, 1844, the line between Washington 
and Baltimore w r as completed, and the whole ap- 
paratus iii working condition. The professor sent 
word to Miss Ellsworth to come and send the first 
dispatch. Accordingly, she sent the first regular 
telegraphic message ever conveyed between distant 
stations. 

"What hath God wrought!" were the words 
of the dispatch. 

On May 27, 1844, the news of the nomination 
of James K. Polk, by the Democratic Convention, 
was sent from Baltimore to Washington. From 
that time forward the telegraph grew rapidly into 
public favor. Besides conferring untold blessings 
on his race, Morse achieved a colossal fortune and 
immortal fame. 



CHAPTER XV. 

MAGNETO-ELECTRICITY — DYNAMOS. 

Faraday discovered, in 1831, that when the 
pole of a permanent magnet was inserted in a coil 
of wire, a current of electricity was induced in the 
coil at the instant of insertion. The current's ex- 
istence, however, was but momentary. Also that 
another momentary current was induced in the 
coil, in the opposite direction, upon the withdrawal 
of the magnet. In these experiments, the ends of 
the coil were in contact with a galvanometer. So 
long as the magnet remained at rest in the coil, 
there was no evidence of electric excitement. 
There is thus a reciprocity between the magnet and 
the current. The magnet produces a current, and 
the current a magnet. 

If, instead of connecting the ends of the wire 
with a galvanometer, they be held in the hands, 



MAGNETO-ELECTRICITY— DYNAMOS. 1 53 

and the magnet be repeatedly inserted and with- 
drawn, a series of severe shocks will be felt. 

If an electro-magnet be rapidly revolved on an 
axis in front of the poles of a large permanent mag- 
net, a series of induced currents will be manifested 
in the wire of the electro-magnet; for, when the 
poles of the electro-magnet come just opposite 
those of the permanent magnet, the electro-magnet 
will be magnetized, and induce a current in its 
helix. When the poles are separated by the revolu- 
tion of the electro-magnet, the electro-magnet dis- 
charges its magnetism, and so induces a current in 
the helix, in a direction opposite to the previous 
current. There are thus in every revolution of the 
electro-magnet four induced currents, two in one 
direction and two in the opposite. The direction 
of the first current is governed by Ampere's for 
mula. 

By constructing an apparatus in such a way that 
an electro-magnet may be rapidly revolved in the 
vicinity of the poles of a large fixed permanent 
magnet, with the addition to the axis of the electro- 
magnet of a commutator, or a break-piece composed 
of alternate ribs of copper and ivory, great streams 
of electricity, and in one direction only, may be 
generated. An instrument of this kind is called 



154 ELECTRICITY AND ITS DISCOVERERS. 

a magneto-electric or dynamo-electric machine, or 
simply dynamo for brevity. Dynamos are multiple 
in form, and have reached great perfection. Dy- 
namo is from the Greek dunamis, power, and is 
applied to electricity in motion, in contradistinc- 
tion to that in the bound or static condition. No 
battery can be constituted to compete with them 
in power ; and they are much more economical and 
far less troublesome than batteries. Though differ- 
ing much in model and variety of structure, all 
dynamos depend on the same principle of magneto- 
electric induction. 

The dynamo answers all the purposes of the 
battery. Its electricity may be employed in elec- 
trolysis, physiology, lighting, motion, etc. 

Saxton, Wilde, Siemens, and Wheatstone, were 
early in the field with machines. But Gramme, of 
Paris, has given us by far the most celebrated 
and, indeed, useful one of them all. His instru- 
ment supplies a powerful current and in a single 
direction, without the aid of commutators. In- 
stead of an electro-magnet or other armature re- 
volving before and in the immediate vicinity of 
the poles of a permanent magnet, the Gramme 
instrument has a wheel revolving vertically be- 
tween the arms of a vertical permanent magnet. 



MAGNETO-ELECTRICITY— DYNAMOS. 155 

This wheel acts the part of armature, and is com- 
posed of an annular band of soft iron, wound 
around with several separate bobbins of insulated 
copper wire, whose ends terminate in radial cop- 
per bands insulated from each other. This arma- 
ture acts the part of a combination battery, each 
bobbin performing the office of a separate cell 
having its positive and negative poles. During 
the revolutions of the wheel, the electricity is 
carried off from each side of the vertical line by 
wire brushes. The vertical is the dividing line 
between the two halves of the circuit. A con- 
stant, steady, powerful current of electricity is 
thus generated. This dynamo can be made of 
any convenient size, and be driven by a steam- 
engine of any number of horse-powers. 

A dynamo of late contrivance is that called 
the Ferranti-Thompson, and is remarkable for 
cheapness and simplicity of construction, but has 
the great drawback of having alternating currents. 

The Ball unipolar dynamo-machine is another 
late invention, in which two armatures are used, 
and in such a way that only one pole of a mag- 
net is presented to each. This apparatus requires 
the assistance of commutators, and demands a 
very high rate of speed 



156 ELECTEICITY AND ITS DISCOVEEEES. 

* 

The superiority of the Gramme dynamos rests 
in the low rate of speed necessary, and the free- 
dom from commutators. Other dynamos require 
in the neighborhood of two thousand revolutions 
in a minute for effective work, causing thus a 
rapid heating up and wearing away of the ma- 
chine. The Gramme dynamos can do all neces- 
sary work with a speed of three hundred revolu- 
tions in a minute, and generate a constant, even 
current, without commutators. 

The dynamos thus far contrived are not well 
suited for telegraphic purposes, as the tension re- 
quired to overcome the resistance of a long cir- 
cuit would demand what as yet seems to be an 
impossible construction. Dynamos are available 
chiefly for electric lighting and electroplating. 

If two dynamos are so employed that the cur- 
rent from the armature of one may pass into the 
armature of the other, the electricity generated 
by the motion of one will move the other. The 
dynamo may thus be used as a motive force, or 
electro-motor, as it is called. Dynamos are so 
used to work machinery and run cars. As an 
electro-motor, however, the dynamo must be said 
to be in its absolute infancy. The longest elec- 
tric railway in the world is in Ireland, between 



MAGNETO-ELECTPJCITY— DYNAMOS. 157 

Portrush and Bushmills, This line is run by a 
stationary dynamo, and is six miles in extent. 

The electricity is conveyed to the motor either 
through the medium of the rails themselves, one 
rail conveying the current to the motor, and the 
other rail conducting it back to the dynamo, or 
by means of an auxiliary conductor. This con- 
ductor runs along between and parallel to the 
rails, and the motor receives the electricity from 
it through a metal brush. This brush is connected 
with the motor, and presses upon the conductor. 
The current is conveyed back to the dynamo by 
way of the rails. 

Electricians are very sanguine of the brilliant 
future in store for their cherished electro-motor. 
The entire absence of smoke and cinders will 
render it unrivaled for tunnel and underground 
travel; and, even in case of collision or other 
accident, a person will have the comfort of being 
killed without being previously scalded by glow- 
ing steam, or roasted by iiery coals! 



CHAPTER XVI. 

THE STORAGE OF ELECTRICITY. 

By the storage of electricity is meant the ac- 
cumulation of a quantity of electric energy, to be 
used afterward at will and to suit convenience. A 
storage-battery, also called a secondary battery, is, 
in truth, an apparatus for transforming electricity. 
It is not the actual collection of the fluid itself, 
after the manner of Lcyden-jars, or prime conduct- 
ors. Electricity can never be stored in this way 
for any useful or commercial purpose. 

When we wind up the spring of a clock, the 
force or energy requisite to do so is stored away, 
to be used afterward in running the clock. When 
we turn a crank to draw up the iron hammer of a 
pile-driver, we have so much energy stored away, 
to be employed in driving down the pile. So, 
when, by the force of the electric current, we 
separate substances that have a great chemical 



THE STORAGE OF ELECTRICITY. 159 

affinity, the force being removed, these substances 
combine again, regenerating the same quantity of 
electricity that it required to separate them. 

In mechanics it is often desirable to transform 
force into speed, or again speed into force. So, in 
electricity, tension may be transformed into quan- 
tity, and quantity again into tension. 

Electric transformers are of two classes; one 
regards tension and the other quantity. The very 
life of the secondary or storage battery hangs on 
Newton'fi principle, " To every action there is an 
equal and contrary reaction." "Without reaction 
we could have no storage of energy. 

In a Darnell's cell zinc is eaten away, and pure 
copper deposited. By forcing a current of elec- 
tricity back through the cell, the copper will be 
eaten away, and zinc deposited. In the deposition 
of the pure zinc, we actually store energy ; for, 
when the pressure is removed, the affinity of the 
oxygen for the zinc being free to assert itself, will 
cause their reunion, and so will generate the same 
quantity of electricity that was required for the 
deposition. 

The chemical affinity of the zinc for the oxygen 
is called its polarization. The force which sepa- 
rates the zinc from combination is called the elec- 



160 ELECTEICITY AND ITS DISCOVERERS. 

tro-motive force ; and the zinc's tendency to resist 
this force, or indeed its polarization, is called its 
counter-electro-motive force. The storage of elec- 
tricity is the overcoming of this polarization, or 
counter-electro-motive force. 

A storage-battery consists of two plates of lead 
placed in a vessel containing acidulated water. A 
current of electricity is sent, by means of an or- 
dinary galvanic battery, from one plate of lead to 
the other. The current decomposes the water, 
sending the oxygen to one plate and the hydrogen 
to the other. The oxygen combines with the lead 
forming peroxide of lead ; and the hydrogen, reach- 
ing the other plate, decomposes any salt of lead it 
may find there, precipitating pure lead, or other- 
wise escaping in the form of gas. The current is 
then reversed, and driven through the arrangement 
in the opposite direction. The current is thus re- 
versed several times, in order to prepare the storage- 
battery, by making the surfaces of the lead plates 
porous, and so capable of holding a great quantity 
of peroxide of lead. 

If the lead plates be connected by wire, after 
the battery has been charged, the oxygen that had 
been forcibly driven from its combination in the 
liquid, seeks to recombine, just as a stone forcibly 



THE STORAGE OF ELECTRICITY. 161 

lifted from the earth seeks to return, and the effect 
of this tendency of the oxygen is to generate an 
electric current in the opposite direction to the 
original one. This is the current that has been 
stored, and is to be utilized as storage, 

Gaston Plante made the first storage-battery in 
1859. It consisted of two sheets of lead, about 
three and one quarter feet square, rolled in a 
cylinder, and placed in a jar filled with dilute 
sulphuric acid. Strips of felt were placed between 
the lead sheets. He prepared his battery for use, 
by sending the current from three Grove cells 
through it several times in opposite directions. He 
then charged it, and permitted it to so stand for 
a short time; he finally discharged it, and it was 
ready for use. 

When the storage-battery is charged, and its 
poles connected, it works like any other battery. 
The metallic lead, combining with the acid, forms 
sulphate of lead ; the liberated hydrogen takes the 
oxygen from the peroxide of lead on the other 
plate, forming water. "When both the lead plates 
are reduced to the same condition, the battery is 
discharged. 

Faure's secondary battery, or accumulator, dif- 
fers from Planters only in the preparation, Faure 



162 ELECTRICITY AND ITS DISCOVERERS. 

saves both time and energy by his method. He 
coats the lead plates with a mixture of minium, 
or red-lead, and sulphuric acid. This red-lead is 
largely changed into sulphate of lead, through the 
action of the acid. The galvanic current, on its 
first action, changes the sulphate of lead upon one 
plate into spongy metallic lead, and upon the other 
plate oxidizes it, forming the peroxide of lead. 

A single cell of either Faure or Plants weighs 
ninety pounds. The box containing these batteries 
is coated with plumber's cement, to withstand the 
action of the acid. The thicker the lead plates, 
the greater will be the storing capacity of the bat- 
teries. A secondary battery should be kept in a 
cool place, as heat diminishes its force. 

In the Brush storage system, lead oxide is 
used in connection with lead plates. The man- 
ner of electric treatment is known only to Mr. 
Brush. He claims a great deal for his system. 

Plante has lately much improved his battery, 
by a new preparatory treatment. 

D'Arsonval's secondary battery has a plate of 
zinc and one of carbon placed in a porous cell 
filled with small shot, the whole impregnated with 
a solution of sulphate of zinc. 

Varley, Kabath, Houston, and Thomson have 



THE STORAGE OF ELECTRICITY. 163 

given their names to storage-batteries. The latest 
improvements in secondary batteries are by Tribe, 
De Lalande, and Chaperon. 

In electric railroading a good system of stor- 
age would be invaluable, as it would obviate the 
necessity of using either the rails or auxiliary 
conductors to convey the fluid from the dynamo 
to the motor and back. For, besides the great 
inconvenience of thus conveying the fluid, it occa- 
sions, moreover, a great loss of current. But the 
accumulators thus far devised are too heavy, too 
expensive, and too prodigal of the primitive cur- 
rent. Only fifty per cent of the invested elec- 
tricity is returned by an accumulator. 

For electric lighting, the accumulator is thus 
far most valuable. It furnishes an even, constant 
current. No matter how many or how few lamps 
may be connected with the battery, they all burn 
with perfect steadiness and uniform power. Each 
lamp takes its exact proportion of the power, and 
no more ; so there is no waste. 

The motive power of a dynamo furnishing 
the electricity for illuminating purposes must 
work with the greatest smoothness. The least 
failure in steadiness on the part of the driving- 
engine produces a flicker in the lights, and a 



161 ELECTRICITY AND ITS DISCOVERERS. 

stoppage for a second would result in total dark- 
ness. The electric current is so sensitive that, 
when a badly laced band from the driving-wheel 
of a steam-engine works a dynamo, the lights in 
a circuit are observed to give a sudden shiver 
every time the laced ends of the band pass over 
the drum. The storage-battery, on the contrary, 
on all occasions furnishes an even flow of cur- 
rent, and so a steady, uninterrupted light. 



CHAPTER XVII. 



THE TELEPHONE. 



The telephone (from the Greek tele, far, and 
phone, voice) is a wonderful instrument of recent 
invention, devoted to the electric transmission of 
speech. The sensation of sound is produced by 
the undulatory or vibratory motions of the air 
impinging on the tympanum or drum of the ear, 
and thence, by means of a delicate chain of bones 
and the fluid of the labyrinth, communicated to 
the auditory nerve. 

The undulations of any elastic body, as well as 
of the air, will produce sound. In fact, solids con- 
vey sound better than either liquids or gases, and 
liquids better than gases. The nature of the sound 
depends upon the class of waves occasioning it. 
The lowest tone audible to the human ear is pro- 
duced by sixteen vibrations in a second, and the 
highest by about sixteen thousand. 

The ear recognizes three varieties in sound — 



166 ELECTRICITY AKD ITS DISCOVERERS. 

tone, intensity, and quality. The tone depends 
on the rapidity of the vibrations ; the intensity on 
the amplitude or depth of the wave ; and the 
quality, according to Miiller, is due to the order 
in which the velocities and changes of density suc- 
ceed each other in the sound-waves which produce 
the tone. 

If, by any means whatever, we can reproduce 
the precise vibrations of a sound, they will make 
the very same impression on the ear as the original 
sound. 

The first attempt at transmitting speech through 
the agency of electricity was made by Philipp Reis, 
a Professor of Natural Philosophy in Friedrichsdorf, 
in 1861. His instrument was a crude one, but the 
principle was correct. Reis was very poor, very 
modest, without influential friends, and of a deli- 
cate constitution, and consequently his invention 
fell through for the time being. Reis's first re- 
ceiver consisted of a helix inclosing an iron rod, 
and fixed upon a hollow sounding-box. Iron rods, 
when magnetized by the closing of an electric cur- 
rent, are slightly increased in length ; and, when 
demagnetized by the breaking of the current, are 
restored to their first length. These differences of 
length in the rod succeed one another in exact ?.c- 



THE TELEPHONE. 167 

cordance with the closing or breaking of the cur- 
rent occasioned by the vibrations of the sound at 
the sending-station, and are communicated by the 
rod to the sounding-box, and thereby rendered 
audible at the receiving-station. The electro-mag- 
net used by Eeis was a knitting-needle wound with 
silk-covered copper wire, and his sounding-box was 
a cigar-box. 

In 1876 the problem of transmitting speech 
electrically was practically solved, and the honor 
of solution is equally claimed by Elisha Gray and 
Graham Bell. It is on record that both took out 
patents on the same day, the 14th of February, 
1876. When the time of Gray's caveat expired, 
he was so engrossed with his harmonic telegraph, 
that he committed the formal error of not having 
it renewed, and so the American courts have pro- 
nounced in favor of Bell's priority. 

In the Bell telephone no battery is employed, 
induced currents doing the work. The action of 
a magnet on a closed circuit has been already 
described, under the head of magneto- electricity. 
When the pole of a magnet is approached to such 
a circuit, an instantaneous current is induced in the 
wire. When the pole is withdrawn, another mo- 
mentary current is induced in a direction opposite 



168 ELECTRICITY AND ITS DISCOVERERS. 

to the former current. The first current is called 
the inverse, because it is opposite to the magnetic 
current itself ; and the last current direct, because 
it is in a similar direction to the magnetic current. 
If a galvanometer be placed in a circuit, the con- 
duct of the currents will be made manifest. If, 
instead of a single approach and withdrawal, the 
magnet be jerked backward and forward repeat- 
edly, corresponding currents will be induced in the 
circuit, as will be seen by the motions of the gal- 
vanometer-needle. If, instead of a single circuit, 
we use a coil or helix, the action will be stronger 
and more manifest. If a core of soft iron be in- 
serted in the helix, it will cause a simultaneous 
action in the whole coil, and so increase the 
strength of the induced currents. If we substi- 
tute a permanent magnet for the soft-iron core, a 
similar effect may be produced in the helix, by 
approaching or withdrawing a soft-iron armature 
to or from the poles of the magnet. The soft-iron 
armature will become magnetized or demagnetized, 
according to its approach to or withdrawal from 
the permanent magnet, and will react on the wire, 
producing induced currents in the helix, whose 
directions are governed by Ampere's formula. 
Every movement of this armature will cause a 



THE TELEPHONE. 169 

proportionate current in the helix. So sensitive 
is this coil, that it responds to the faintest stir of 
the armature. 

If this armature is replaced by a delicate iron 
disk, which, under the influence of sound, will 
vibrate in a manner similar to the tympanum or 
drum of the ear, the alternate movements of the 
disk will be transformed into the induced cur- 
rents, and these will be stronger or weaker, more 
or less definite, according to the range and com- 
plexity of the vibrations. These divers currents 
flow along the wire to the receiving-station, where 
they react on another similar iron disk through 
means of an electro-magnet, reproducing a fac- 
simile of the original vibrations. It is not neces- 
sary that the magnetic core, however, should be 
of soft iron, since the vibratory effects may fol- 
low from differential as well as from direct mag- 
netization ; and so in the receiver, as in the trans- 
mitter, a permanent magnet may be used. Thus 
electricity affords the means of calling into life, 
at any given distance, vibrations similar to the 
vibrations that have been produced, and in this 
way to give out again in one place tones that 
have been produced in another place. 

It will be understood that the waves or undu- 

8 



170 ELECTRICITY AND ITS DISCOVERERS. 

lations themselves of sound are not carried along 
the wire; the electric fluid alone traverses the 
circuit from one station to another. The vibra- 
tions are not carried, but reproduced ; for it has 
really been objected that this awful speed of sound 
overthrows the undulatory theory. Sound travels 
in the air at the rate of eleven hundred and twen- 
ty-five feet per second, in water four and one half 
times, in silver nine times, in cast-iron ten times, 
and in hammered iron, where it attains its greatest 
velocity, seventeen times more rapidly. But this 
new advance on the old records upsets entirely, 
it is said, the deductions of Helmholtz. But, in- 
deed, the speed of sound is neither increased nor 
changed, the sound is simply reproduced. 

The Bell telephone consists of a circular wood- 
en box at the extremity of a wooden handle. A 
magnetic bar runs through the handle, with one 
of its poles reaching to about the center of the 
box. This pole of the magnet is surrounded with 
a helix of very fine copper wire. A screw is 
fitted to the other pole of the bar, by which it 
can be moved backward or forward, for the regu- 
lation of the instrument. The ends of the helix 
run down through the handle to its opposite end, 
and are thence connected with the line-wires. 



THE TELEPHONE. 171 

One of these wires is borne over insulators to the 
distant station, and the other is run into the 
ground, as in the ordinary telegraphic circuit. 
The vibrating plate is a very thin disk of iron, 
placed immediately in front of that pole of the 
magnet projecting into the box. The rim of the 
disk is fastened to the wooden box by means of 
an India-rubber ring. The disk should be as 
near as possible to the magnetic pole, without 
ever actually touching it, while vibrating under 
the sound of the voice. The mouth-piece is fun- 
nel-shaped, the small end of the funnel very 
close to the vibrating disk, but leaving a small 
space between the edge of the hole of the funnel 
and the disk. The wooden box should be so 
constituted as to act the part of a sounding-box. 
There are two of these telephones at each station, 
one to talk into, and which is usually fixed, and 
the other to hold to the ear. 

A system of alarm-bells is attached to the tele- 
phone, in order to give notice when an exchange 
of correspondence is desired. An electric bell is 
attached to the main circuit, through the medium 
of a commutator. A wire from the bell, and- one 
from the telephone, are joined to this commutator, 
which is in connection with the main circuit. This 



172 ELECTRICITY AND ITS DISCOVERERS. 

commutator is made to act automatically. A forked 
hook is attached to a spring moving up and down 
between the two contacts of the commutator. 
When the telephone-handle is fastened to the hook, 
its weight carries down the spring, and connects 
the main circuit with the bell. When the tele- 
phone is removed from its support, the spring, 
being relieved of its weight, flies up to the higher 
contact, and connects the telephone with the main 
circuit. Commutators are also placed in the bell- 
wires, to make connection, when desired, with the 
main current, by either pushing an electric button 
or turning a winch, according to the apparatus. 

The battery telephone of Mr. Edison is much 
more powerful than Mr. Bell's, transmitting sound 
to a greater distance and with more distinctness. 
Edison employs a battery in his system, and his 
apparatus is much more complicated than Mr. 
Bell's. In battery telephones, secondary coils and 
induction-currents are used for the main circuit. 

Modifications and improvements unnumbered 
have been introduced into the structure of the 
telephone in the last few years. When many 
stations are joined together, as in a city, any two 
are put in communication by means of a switch- 
board located at a central station. 



THE TELEPHONE. 173 

An excellent form of battery telephone has 
been lately devised by George M. Hopkins, of 
Brooklyn, New York. The disk or diaphragm is 
made of mica, and is one and three quarters of an 
inch in diameter. The surfaces between which the 
diaphragm is clamped are of vulcanite, a material 
not liable to warp. It is said that this instrument 
acts as well on the Postal Telegraph Company's 
wire between New York and Cleveland, a dis- 
tance of six hundred and fifty miles, as the 
ordinary telephone does over a distance of 
three miles. Telephonic communication was suc- 
cessfully carried on through this same instru- 
ment, over the same company's line between 
New York and Chicago, a distance of one thou- 
sand miles. 

The Postal Telegraph Company has the very 
best conducting wire yet devised. It is a com- 
pound wire, having a core of steel with a copper 
covering. The steel gives tensile strength and elas- 
ticity, and the copper conductivity. This wire is 
computed to have six times the conducting capacity 
of an iron wire of equal weight. This wire be- 
tween New York and Chicago has a resistance of 
fifteen hundred ohms, the best iron wire over the 
same route has a resistance of ten thousand ohms, 



174 ELECTRICITY AND ITS DISCOVERERS. 

and the average iron wire in common use offers a 
resistance of fifteen thousand ohms. 

Myron L. Baxter, of the United States War 
Department, is the latest claimant for telephonic 
honors. He has discovered that, by throwing the 
whole battery current into the circuit wire, and 
connecting the diaphragm by a wire with the 
ground, the vibrations of the diaphragm caused 
by the voice can be utilized to make or break the 
current. The effects produced by this system are 
said to be wonderful indeed. Over a copper- 
covered wire running alongside the Erie Railroad, 
speech was distinctly audible between parties seven 
hundred and twenty-four miles apart. 

Well, indeed, has Sir William Thomson called 
the telephone " the wonder of wonders," even in 
the wonder-land of electricity ! 



CHAPTEK XVIII. 

THE AURORA BOREALIS, OR RED LIGHTS OF THE 
NORTH. 

The aurora borealis is a luminous phenomenon 
that lights up at night the northern heavens. In 
the neighborhood of the Arctic Circle it is almost 
a permanent visitor, but north or south of this 
circle its appearance is less frequent. To the in- 
habitants of temperate latitudes it is rarely visible, 
and never in all its matchless beauty. Indeed, the 
beauty of this splendid meteor is beyond the reach 
of language, and must be seen in its Arctic glory 
to be adequately prized. 

In winter, when the sun travels south along the 
ecliptic, the Arctic regions are deprived more and 
more of his beams, until at last he hides himself 
completely from view for weeks together. In such 
times the northern light is, indeed, a welcome visit- 



176 ELECTRICITY AND ITS DISCOVERERS. 

ant to the dwellers on the shores of the Polar Sea. 
The auroral light is sufficient to allow them to go 
about the ordinary purposes of life. This light is 
brighter than the moon's in its first quarter, but 
scarcely ever reaches the luster of the full moon, 
though it is said by travelers to have enabled them 
to read ordinary print. 

The aurora sometimes presents the appearance 
of a bank of dingy clouds, having the form of a 
circular segment resting its ends on the eastern 
and western horizon. The upper portion of this 
segment is illumined by a bluish-white band of 
light, averaging 3° in depth. The matter com- 
posing the cloud-bank is so extremely tenuous 
that very faint stars are visible through it, their 
light passing through undimmed. This cloud be- 
gins to assume shape soon after the sun's setting, 
and, as the twilight fades, it gradually lights up, 
sometimes throwing out streamers at regular in- 
tervals, presenting the precise appearance of a 
comb. The segment is a portion of a circle whose 
center is the earth's magnetic pole. This pole is 
at present located in the Island of Boothia 
Felix. 

Again, the aurora borealis sometimes appears in 
the pillar-form. Large pillars of light seem built 



THE AURORA BOREALIS. 177 

up against the northern sky, leaning in a direction 
parallel to the dipping-needle. These pillars or 
streamers are in perpetual motion, and look as if 
they were painted on a flag or curtain incessantly 
swayed by the wind. 

The auroral light varies very much as regards 
color. It being chiefly an electric phenomenon, 
the color is determined by the rarity or density of 
the atmospheric region through which the current 
passes. It is well established that the most rarefied 
air produces a white light ; the most dry air red ; 
and the most damp produces yellow streaks. " In 
the higher latitudes," says Humboldt, "the pre- 
vailing color of the polar light is usually white, 
while it presents a milky hue when the aurora is 
of faint intensity. When the colors brighten, they 
assume a yellow tinge ; the middle of the broad 
ray becomes golden yellow, while both the edges 
are marked by separate bands of red and green. 
"When the radiation extends in narrow bands, the 
red is seen above the green. When the aurora 
moves sidewise from left to right, or from right 
to left, the red appears invariably in the direction 
toward which the ray is advancing, and the green 
remains behind." 

The aurora is not at all local in its character, 



178 ELECTRICITY AND ITS DISCOVEREPwS. 

as it has been witnessed simultaneously in Europe, 
Asia, and America. Like the rainbow, it appears 
differently to different observers. While to all it 
preserves its characteristic features, still each one 
sees his own aurora, as he does his own rainbow. 
It is owing to this peculiarity that there has been 
such a vast discrepancy in the estimate of its 
height. In trying to find the aurora's parallax, 
no two observers can see the same point, at the 
same time, in the same way. In all probability, 
its average height may be set down at seventy 
miles above the earth's surface. Some auroras are 
much higher, some much lower. There is a pop- 
ular belief that a crackling noise accompanies the 
aurora, resembling the swaying of silk in the wind ; 
but the celebrated travelers and voyagers, Parry, 
Franklin, Richardson, Gieseke, Bravais, Wrangel, 
and Anjou, never heard it ; so that it must, in all 
probability, be attributed to the cracking of dis- 
tant ice-fields. 

It is quite safe to say that the aurora borealis 
is of electric origin, and is very intimately con- 
nected with the magnetism of the earth. It very 
sensibly affects the magnetic needle, causing it to 
tremble and deviate from point to point. Its un- 
usual splendor presages elect lie storms, and its 






THE AURORA BOREALIS. 179 

frequency and grandeur are indexes of solar par- 
oxysms. 

Sun-spots are great chasms in the sun's shells, 
rent and torn by solar explosions. These chasms 
are enormous in size, one of them, for instance 
— but, indeed, the greatest known to astronomy — 
measured 153,500 miles in diameter, and would 
easily hold one hundred globes the dimensions of 
the earth. An increase in the number of spots 
shows unwonted activity in the great central orb. 
These spots have a periodicity. They reach their 
greatest number every eleven years. The auroral 
displays, as regards brilliancy and frequency, fol- 
low the same period. In fact, the solar spots in- 
fluence the aurora borealis. We have had a very 
striking and signal proof of this quite recently. 
On April 16, 1882, two immense spots appeared 
upon the sun, and presented the unusual spectacle 
of undergoing perceptible change right under the 
eye of the observer. Commotions of an unwonted 
character were going on in the snn. The magnet- 
ism of the earth almost immediately responded to 
the magnetic storm in the sun. An aurora of 
great splendor made its appearance that night. 
A magnetic storm raged on the earth the next 
day. Messages were sent along the wires with- 



180 ELECTRICITY AND ITS DISCOVERERS. 

out the use of batteries ; in some places the 
wires refused to work, and the Atlantic cable 
was crippled. 

From the 12th to the 19th of November, 1882, 
a tremendous spot, exceeding in magnitude the 
April spots, traveled across the sun's disk. Dur- 
ing a portion of this period, a very hurricane of 
magnetic forces raged on the earth, culminating, 
on the 17th, in one of the most terrific magnetic 
storms ever recorded. During all this time fine 
auroras were observed in Europe, but the chief 
displays in this country were on the nights of the 
17th and 19th, The telegraph wires were again 
worked without batteries. Sparks of fire leaped 
from wires and instruments. The operators were 
appalled, switch-boards were burned, and keys 
melted. The electric disturbance was without a 
parallel. The auroral displays were wonderfully 
brilliant. An immense band of fire spanned the 
northern heavens, and a blending of rose-color, 
green, violet, yellow, and orange lights added 
beauty and variety to the scene. 

The la&t mighty spot was in the beginning of 
last October, just after the passage of the comet, 
when beautiful auroras appeared in England, Scot- 
land, and Western Europe. 



THE AURORA BOREALIS. 181 

The years 1881 and 1882, and beginning of 
1883, corresponded to the maximum of the sun- 
spot period, and, sure enough, they have been re- 
markable for auroras and magnetic disturbances 
on our planet's surface. 

Lenstrom has lately given us a direct and defi- 
nite proof of the electrical nature of the aurora 
borealis. In November and December, 1882, he 
produced artificial auroras at Sodankyla and Kul- 
tala, Lapland. The first experiment was made on 
the mountain of Oratunturi, near the village of 
Sodankyla; and the second, on the mountain of 
Pietarintunturi, near Kultala. Both experiments 
were, in the main, identical. A long copper wire 
was bent into a series of squares within squares, 
and placed, in an upright position, on the top of 
the mountain. The bent wire presented a total 
space of over nine hundred square yards. At dis- 
tances of more than one half a yard, along the 
whole wire, on opposite sides, were projected points 
of tin. The copper wire was connected with a 
galvanometer, and thence with the earth. The ex- 
periments were entirely successful. Artificial au- 
roras were called into life, and the fact mainly 
established that the aurora borealis is an electric 
light. 



182 ELECTRICITY AND ITS DISCOVERERS. 

Those who have gone down in ships to the 
southern seas tell of similar auroras streaking the 
heavens toward the south magnetic pole. The 
northern and southern lights are now classed to- 
gether, and called very properly the polar lights. 



APPENDIX. 



EXPERIMENTAL INVESTIGATION OF TABLE-MOVING.* 

BY MICHAEL FARADAY. 

TnE object which I had in view in this in- 
quiry was not to satisfy myself — for my conclusion 
had been formed already on the evidence of those 
who had turned tables — but that I might be en- 
abled to give a strong opinion, founded on facts, 
to the many who applied to me for it. Yet the 
proof which I sought for, and the method fol- 
lowed in the inquiry, were precisely of the same 
nature as those which I should adopt in any other 
physical investigation. The parties with whom I 
have worked were very honorable, very clear in 
their intentions, successful table-movers, very de- 
sirous of succeeding in establishing the existence 
of a peculiar power, thoroughly candid, and very 
effectual. It is with me a clear point that the 
table moves when the parties, though they strongly 

* From the London " Athenaeum," July 2, 1853. 



184: ELECTRICITY AND ITS DISCOVERERS. 

wish it, do not intend, and do not believe that 
they move it by ordinary mechanical power. They 
say the table draws their hands; that it moves 
first, and they have to follow it, that sometimes it 
even moves from under their hands. With some 
the table will move to the right or left according 
as they wish or will it, with others the direction 
of the first motion is uncertain ; but all agree 
that the table moves the hands, and not the hands 
the table. Though I believe the parties do not 
intend to move the table, but obtain the result 
by a quasi-m voluntary action, still I had no doubt 
of the influence of expectation upon their minds, 
and through that upon the success or failure of 
their efforts. 

The first point, therefore, was to remove all 
objections due to expectation, having relation to 
the substances which I might desire to use : so, 
plates of the most different bodies, electrically 
speaking, namely, sand-paper, mill-board, glue, glass, 
moist clay, tin-foil, card-board, gutta-percha, vul- 
canized rubber, wood, etc., were made into a bun- 
dle and placed on a table under the hands of a 
turner. The table turned. Other bundles of 
other plates were submitted to different persons 
at other times, and the tables turned. Hence- 
forth, therefore, these substances may be used in 
the construction of apparatus. Neither during 
their use nor at other times could the slightest 
trace of electrical or magnetic effects be obtained. 



APPENDIX. 185 

At the same trials it was readily ascertained that 
one person could produce the effect ; and that the 
motion was not necessarily circular, but might be 
in a straight line. No form of experiment or 
mode of observation that I could devise gave me 
the slightest indication of any peculiar natural 
force. No attractions, or repulsions, or signs of 
tangential power appeared, nor anything which 
could be referred to other than the mere mechani- 
cal pressure exerted inadvertently by the turner. 
I therefore proceeded to analyze this pressure, or 
that part of it exerted in a horizontal direction — 
doing so, in the first instance, unawares to the 
party. A soft cement, consisting of wax and tur- 
pentine, or wax and pomatum, was prepared. Four 
or five pieces of smooth, slippery card- board were 
attached one over the other by little pellets of the 
cement, and the lower of these to a piece of 
sand-paper resting on the table; the edges of 
these sheets overlapped slightly, and on the under 
surface a pencil-line was drawn over the laps so 
as to indicate position. The upper card-board 
was larger than the rest, so as to cover the 
whole from sight. Then the table-turner placed 
the hands upon the upper card, and we waited 
for the result. Now, the cement was strong 
enough to offer considerable resistance to me- 
chanical motion, and also to retain the cards in 
any new position which they might acquire, and 
yet weak enough to give way slowly to a con- 



186 ELECTRICITY AND ITS DISCOVERERS. 

tinned force. "When at last the tables, cards, and 
hands all moved to the left together, and so a 
true result was obtained, I took up the pack. 
On examination, it was easy to see, by the dis- 
placement of the parts of the line, that the hand 
had moved farther than the table, and that the 
latter had lagged behind ; that the hand, in fact, 
had pushed the upper card to the left, and that 
the under cards and the table had followed and 
been dragged by it. In other similar cases when 
the table had not moved, still the upper card was 
found to have moved, showing that the hand had 
carried it in the expected direction. It was evi- 
dent, therefore, that the table had not drawn the 
hand and person round, nor had it moved simultane- 
ously with the hand. The hand had left all things 
under it behind, and the table evidently tended 
continually to keep the hand back. 

The next step was to arrange an index, which 
should show whether the table moved first, or 
the hand moved before the table, or both moved 
or remained at rest together. At first this was 
done by placing an upright pin fixed on a leaden 
foot upon the table, and using that as the ful- 
crum of a light lever. The latter was made of a 
slip of foolscap paper, and the short arm, about 
one quarter of an inch in length, was attached to 
a pin proceeding from the edge of a slipping 
card placed on the table, and prepared to receive 
the hands of the table-turner. The other arm, of 



APPENDIX. 187 

eleven and one half inches long, served for the in- 
dex of motion. A coin laid on the table marked 
the normal position of the card and index. At 
first the slipping card was attached to the table by 
the soft cement, and the index was either screened 
from the turner, or the latter looked away ; then, 
before the table moved, the index showed that 
the hand was giving a resultant pressure in the 
expected direction. The effect was never carried 
far enough to move the table, for the motion of 
the index corrected the judgment of the experi- 
menter, who became aware that, inadvertently, a 
side force had been exerted. The card was now 
set free from the table, i. e., the cement was re- 
moved. This, of course, could not interfere with 
any of the results expected by the table-turner, 
for both the bundle of plates spoken of and sin- 
gle cards had been freely moved on the tables 
before ; but now that the index was there, wit- 
nessing to the eye, and through it to the mind, 
of the table-turner, not the slightest tendency to 
motion either of the card or of the table occurred. 
Indeed, whether the card was left free or attached 
to the table, all motion or tendency to motion 
was gone. In one particular case there was rela- 
tive motion between the table and the hands : I 
believe that the hands moved in one direction ; 
the table-turner was persuaded that the table moved 
from under the hand in the other direction ; a 
gauge, standing upon the floor, and pointing to 



188 ELECTRICITY AND ITS DISCOVERERS. 

the table, was therefore set up on that and some 
future occasions, and then neither motion of the 
hand nor of the table occurred. 

A more perfect lever apparatus was then con- 
structed in the following manner : Two thin boards, 
nine and a half inches by seven inches, were pro- 
vided ; a board, nine by five inches, was glued to 
the middle of the under side of one of these (to be 
called the table-board), so as to raise the edges free 
from the table ; being placed on the table, near and 
parallel to its side, an upright pin was fixed close 
to the farther edge of the board, at the middle, to 
serve as the fulcrum for the indicating lever. Then 
four glass rods, seven inches long and one fourth of 
an inch in diameter, were placed as rollers on differ- 
ent parts of this table-board, and the upper board 
placed on them ; the rods permitted any required 
amount of pressure on the boards, with a free 
motion of the upper on the lower to the right and 
left. At the part corresponding to the pin in the 
lower board, a piece was cut out of the upper board, 
and a pin attached there which, being bent down- 
ward, entered the hole in the end of the short arm 
of the index-lever; this part of the lever was of 
card - board ; the indicating prolongation was a 
straight hay-stalk fifteen inches long. In order to 
restrain the motion of the upper board on the 
lower, two vulcanized rubber rings were passed 
round both, at the parts not resting on the table ; 
these, while they tied the boards together, acted 



APPENDIX. 189 

also as springs; and while they allowed the first 
feeblest tendency to motion to be seen by the index, 
exerted, before the upper board had moved a quar- 
ter of an inch, sufficient power in pulling the upper 
board back from either side to resist a strong 
lateral action of the hand. All being thus ar- 
ranged, except that the lever was away, the two 
boards were tied together with string, running par- 
allel to the vulcanized rubber springs, so as to be 
immovable in relation to each other. They were 
then placed on the table, and a table-turner sat down 
to them; the table very shortly moved in due 
order, showing that the apparatus offered no im- 
pediment to the action. A like apparatus, with 
metal rollers, produced the same result under the 
hands of another person. The index was now put 
into its place and the string loosened, so that the 
springs should come into play. It was soon seen, 
with the party that could will the motion in either 
direction (from whom the index was purposely hid- 
den), that the hands were gradually creeping up in 
the direction before agreed upon, though the party 
certainly thought they were pressing downward 
only. When shown that it was so, they were truly 
surprised; but when they lifted up their hands 
and immediately saw the index return to its normal 
position, they were convinced. When they looked 
at the index and could see for themselves whether 
they were pressing truly downward or obliquely, 
so as to produce a resultant in the right- or left- 



190 ELECTRICITY AND ITS DISCOVERERS. 

handed direction, then such an effect never took 
place. Several tried for a long while together, and 
with the best will in the world ; but no motion, 
right or left, of the table, or hand, or anything else, 
occurred. 

I think the apparatus I have described may be 
useful to many who really wish to know the truth 
of nature, and would prefer that truth to a mis- 
taken conclusion ; desired, perhaps, only because it 
seems to be new or strange. Persons do not know 
how difficult it is to press directly downward or in 
any given direction against a fixed obstacle ; or even 
to know only whether they are doing so or not, 
unless they have some indicator which, by visible 
motion or otherwise, shall instruct them ; and this 
is more especially the case when the muscles of the 
fingers and hand have been cramped and rendered 
either tingling, or insensible, or cold, by long-con- 
tinued pressure. If a finger be pressed constantly 
into the corner of a window-frame for ten minutes 
or more, and then, continuing the pressure, the 
mind be directed to judge whether the force, at a 
given moment, is all horizontal, or all downward, or 
how much is in one direction and how much in the 
other, it will find great difficulty in deciding, and 
will at last become altogether uncertain — at least, 
such is my case. I know that a similar result 
occurs with others ; for I have had two boards ar- 
ranged, separated, not by rollers but by plugs of 
vulcanized rubber, and with the vertical index; 



APPENDIX. 191 

when a person, with his hands on the upper board, 
is requested to press only downward, and the index 
is hidden from his sight, it moves to the right, to 
the left, to him, and from him, and in all horizontal 
directions ; so utterly unable is he strictly to fulfill 
his intention without a visible and correcting in- 
dicator. 

Now, such is the use of the instrument with the 
horizontal index and rollers : the mind is instructed, 
and the involuntary or quasi-in voluntary motion is 
checked in the commencement, and therefore never 
rises up to the degree needful to move the table, or 
even permanently the index itself. No one can 
suppose that looking at the index can in any way 
interfere with the transfer of electricity or any 
other power from the hand to the board under it, 
or to the table. If the board tends to move, it may 
do so, the index docs not confine it ; and if the 
table tends to move, there is no reason why it 
should not. If both were influenced by any power 
to move together, they may do so — as they did, in- 
deed, when the apparatus was tied, and the mind 
and muscles left unwatched and unchecked. 



Royal Institution, June 27, 1853. 



M. Faeaday. 

at- 



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" It is a bold enterprise, and its very boldness gives it a peculiar fas- 
cination. The vast range of the survey and the multitude of witnesses of 
every age and clime which the author passes in review yield the reader a 
decidedly new sensation, something like that of making a voyage round the 
earth in mid-air." — Home Journal, 

" It is impossible to withhold respect for the ingenious logic and in- 
dustrious scholarship which mark its pages." — Chicago Tribune. 

" This theory ... is set forth with the dexterity and earnestness with 
which in a previous work the author tried to prove the whilom existence 
of the fabled Atlantis, and it is equally certain to rouse the curiosity and 
enchain the attention of a large body of readers." — New York Sun. 

STELLAR THEOLOGY AND MASONIC ASTRONOMY; 

Or, The Origin and Meaning of Ancient and Modern Mysteries Ex- 
plained. By Robert Hewitt Brown, 32°. With numerous Illustra- 
tions by the author, including Diagram of the Zodiac, and the Sum- 
mer and Winter Solstices, in colors. Small 4 to, cloth, $2.00. 

THE ANCIENT BRONZE IMPLEMENTS, WEAPONS, 
AND ORNAMENTS OF GREAT BRITAIN AND IRE- 
LAND. By John Evans, D. C. L., LL. D., etc., author of u The 
Ancient Stone Implements, Weapons, and Ornaments of Great Brit- 
ain." With Five Hundred and Forty Illustrations. One vol., 8vo, 
509 pages. Cloth, $5.00. 

VOLCANOES : What they Are and what they Teach. By J. W. Judd, 
Professor of Geology in the Royal School of Mines (London). With 
96 Illustrations. 12mo. Cloth, §2.00. 

" In no field has modern research been more fruitful than in that of 
which Professor Judd gives a popular account in the present volume. The 
great lines of dynamical, geological, and meteorological inquiry converge 
upon the grand problem of the interior constitution of the earth, and the 
vast influence of subterranean agencies. . . . His book is very far from 
being a mere dry description of volcanoes and their eruptions ; it is rather 
a presentation of the terrestrial facts and laws with which volcanic phe- 
nomena are associated." — Popular Science Monthly. 

THE STUDY OF ROCKS. An Elementary Text-Book in Petrol- 
ogy. With Illustrations. By Frank Kutley, of the English Geo- 
logical Survey. 16mo. Cloth, $1.75. 



New York: D. APPLETON k CO., 1, 3, k 5 Bond Street. 



D. APPLETON & CO.'S PUBLICATIONS. 



ERRORS IS THE USE OF ENGLISH. By the late William 

B. Hodgson, LL. D., Professor of Political Economy in the University 

of Edinburgh. American revised edition. 12mo, cloth, $1.50. 

" This posthumous work of Dr. Hodgson deserves a hearty welcome, for it is 
sure to do good service for the object it has in view— improved accuracy in the 
use of the English language. . . . Perhaps its chief use will be in very distinctly 
proving with what wonderful carelessness or incompetency the English language 
is generally written. For the examples of error here brought together are not 
picked from obscure or inferior writings. Among the grammatical sinners whose 
trespasses are here recorded appear many of our best-known authors and publi- 
cations."— The Academy. 

THE ENGLISH GRAMMAR OF WILLIAM COBBETT. 

Carefully revised and annotated by Alfred Ayres. With Index. 
18mo, cloth, extra, $1.00. 

44 1 know it well, and have read it with great admiration. 1 '— Richard Grant 
White. 

11 Cobbett's Grammar is probably the most readable grammar ever written. 
For the purposes of self-education it is unrivaled. Persons that studied grammar 
when at school and failed to comprehend its principles— and there are many such 
— as well as those that never have studied grammar at all, will find the book 
specially suited to their needs. Any one of average intelligence that will give it 
a careful reading will be rewarded with at least a tolerable knowledge of the 
subject, as nothing could be more simple or more lucid than its expositions."— 
From the Preface. 

THE ORTHOEPIST : A Pronouncing Manual, containing about 

Three Thousand Five Hundred Words, including a Considerable 

Number of the Names of Foreign Authors, Artists, etc.. that are 

often mispronounced. By Alfred Ayres. 18mo, cloth, extra, §1.00. 

" It gives us pleasure to say that we think the author, in the treatment of this 
very difficult and intricate subject, English pronunciation, gives proof of not only 
an unusual degree of orthoepical knowledge, but also, for the most part, of rare 
judgment and taste."— Joseph Thomas, LL. D., in Literary World. 

THE VERBALIST : A Manual devoted to Brief Discussions of the 
Right and the Wrong Use of Words, and to some other matters of 
Interest to those who would Speak and Write with Propriety, includ- 
ing a Treatise on Punctuation. By Alfred Ayres. 18mo, cloth, 
extra, $1.00. 

" This is the best kind of an English grammar. It teaches the right use of 
our mother-tongue by giving instances of the wrong use of it, and showing why 
they are wrong."— The Churchman. 

" Every one can learn something from this volume, and most of us a great 
deal.*— Springfield Republican. 



New York : D. APPLETON & CO., 1, 3, & 5 Bond Street 



D. APPLETON & 00/8 PUBLICATIONS. 

A GEOGRAPHICAL READER. A Collection of Geographical 
Descriptions and Narrations, from the best Writers in English Lit- 
erature. Classified and arranged to meet the wants of Geographical 
Students, and the higher grades of reading classes. By Jame3 
Johonnot, author of " Principles and Practice of Teaching." 12mo, 
cloth, $1.25. 

u Mr. Johonnot has made a good hook, which, if judiciously used, will stop 
the immense waste of time now spent in most schools in the study of geography 
to little purpose. The volume has a good number of appropriate illustrations, 
and is printed and bound in almost faultless style and taste."— National Journal 
of Education. 

It is original and unique in conception and execution. It is varied in style, 
and treats of every variety of geographical topic. It supplements the geograph- 
ical text-books, and, by giving additional interest to the study, it leads the pupil 
to more extensive geographical reading and research. It is not simply a collec- 
tion of dry statistics and outline descriptions, hut vivid narrations of great liter- 
ary merit, that convey useful information and promote general culture. It con- 
forms to the philosophic ideas upon which tne new education is based. Its 
selections are from the best standard authorities. It is embellished with numer- 
ous and appropriate illustrations. 

A NATURAL HISTORY READER, for Schools and IIomes. 

Beautifully illustrated. Compiled and edited by James Johonnot. 

12mo, cloth, $1.25. 

" The natural turn that children have for the country, and for birds and beasts, 
wild and tame, is taken advantage of very wisely by Mr. Johonnot, who has had 
experience in teaching and in making school-books. His selections are generally 
excellent. Articles by renowned naturalist?, and interesting papers by men 
who, if not renowned, can put things pointedly, alternate with serious and 
humorous verse. ' The Popular Science Monthly' has furnished much material. 
The 'Atlantic' and the works of John Burroughs are contributors also. There 
are illustrations, and the compiler has some senHble advice to offer teachers in 
regard to the way in which to interest young people in matters relating to na- 
ture."— New York Times. 

AN HISTORICAL READER, for Classes in Academies, High- 
Schools, and Grammar-Schools. By Henry E. Shepherd, M. A. 
12mo, cloth, $1.25. 

u This book is one of the most important text-hooks issued within our recol- 
lection. The preface is a powerful attack upon the common method of teaching 
history by means of compendiums and abridgments. Professor Shepherd has 
* long advocated the beginning of history-teaching by the use of graphic and lively 
sketches of those illustrious characters "around whom the historic interest of each 
age is concentrated.' This volume is an attempt to embody this idea in a form 
for practical use. Irving, Motley. Macaulay, Preicott, Greene, Froude, Momm- 
sen, Guizot, and Gibbon are among the authors represented ; and the subjects 
treated cover nearly all the sreatest events and greatest characters of time. The 
hook is one of indescribable interest. The boy or girl who is not fascinated by 
it must be dull indeed. Blessed be the day when it shall be introduced into our 
high-schools, in the place of the dry and wearisome ' facts and figures ' of the 
4 general history ' I "—Iowa Normal Monthly. 



New York: D. APPLETON & CO., 1, 3, & 5 Bond Street 



D. APPLETON & CO.'S PUBLICATIONS, 

RETROSPECT OF A LONG LIFE, from 1815 to 1883. By 
S. C. Hall, F.S.A. With Portraits of Mr. and Mrs. S. C. Hall. 
Crown Svo, cloth, $2.50. 

Containing: Reminiscences of almost all the celebrated Literary Men for the 
last half-century— Tennyson, Charles Dickens. Hawthorne, Charles Lamb. Savage 
Landor, Lady Blessington, Carlvle, Longfellow, Coleridge. De Quincey, Miss 
Edgeworth, Godwin, Hallam, Hazlitt, Tom Hood, Leigh Hunt, Father Prout, 
Mrs. Norton, Rogers, John Ruskin, Sydney Smith, Wordsworth, Edmund Keati, 
Macready, Keeley, Miss O'Neil, George Cruikshank, Samuel Prout. Turner. Wil- 
kie, Beranger, Fenimore Cooper, Lord Lytton, Palmerston, Macaulay, Beacons- 
field, Canning, George IV, Lyndhurst, Brougham, etc., etc. 

Mr. Hall is well known as the editor for many years of the London "Art Jour- 
nal,' 1 as author of "The Stately Homes of England," and numerous books pre- 
pared in conjunction with his wife, Mrs. S. C. Hall. Mr. Hall was at one time a 
parliamentary reporter: he succeeded Campbell as editor of " The New Monthly 
Magazine," and was editorially associated with other periodicals. Daring his 
long connection with letters he met many men of note ; in fact, he has something 
to say in this book of almost every person who has occupied public attention 
during the past sixty years. 

" It was eminently proper and desirable that Mr. Hall should write his recol- 
lections, for his life, in addition to its great length, was passed in circumstances 
that fitted him to write of persons and events in which the world has an undying 
interest. The book is very readable, and it is worth being read. Mr. Hall's rec- 
ollections of Americans are not numerous, but they are always appreciative." — 
New York Times. 

"Mr. S. C. Hall has given us not a diary or compilation of second-hand mate- 
rials, but genuine reminiscences of men and events that he has personally 6een 
in the course of an active professional career that covers more than sixty years. 
He has made an exceedingly entertaining book, that deserves a place of honor 
among the volumes of reminiscences that have of late been issued with such pro- 
fusion from the American press."— Xew York Sun. 

JOII1V KEESE : Wit and Litterateur. A Biographical Memoir. By 

William L. Keese. Small 4to, cloth, gilt top, $1.25. 

John Keese was a popular book-auctioneer of New York thirty years ago, 
whose witticisms were the town talk. '* If John Keese should quit the auctioneer 
business, I should die of ennui.'" exclaimed one of his admirers. Mr. Keese was 
known to all the literary people of his day, and these memoirs contain reminis- 
cences and anecdotes of literary circles in New York a generation ago that will 
be valued by those who like glances at past local conditions. 

LANDMARKS OE ENGLISH LITERATURE. By Henry 
J. Xicoll. 12mo, vellum cloth, $1.75. 

"The plan adopted in this book has been to deal solely with the very greatest 
names in the several departments of English literature — with those writers whose 
works are among the most imperishable glories of Britain, and with whom it is 
a disgrace for even the busiest to remain unacquainted."— From Preface. 

"We can warmly recommend this excellent manual."— St. James's Gazette. 

" The ' Landmarks of English Literature ' is a work of exceptional value. It 
reveals scholarship and high literary ability. Mr. Nicoll has a proper conception 
of the age in which he lives, and of its requirements in the special line in which 
he has attempted to work."— Xew York Herald. 



New York : D. APPLETOX k CO., 1, 3, Iz 5 Bond Street. 



D. APPLETON & CO/8 PUBLICATIONS. 

APM-ETONS* HOME BOOKS. Complete in 12 volumes, 12mo. 
Handsomely printed, and bound in cloth, flexible, with illuminated 
design, 60 cent3 each. 

The twelve books are also put up in three volumes, four books to the volume 
in the following order, handsomely bound in cloth, decorated. Price of each of 
these volumes, $2.00, or $6.00 the set, in box. 

I. 
EUILDING A HOME. By A. F. Oaket. Illustrated. 

II. 
HOW TO FURNISH A HOME. By Ella Rodman Church. Illustrated 

III. 
THE HOME GARDEN. By Ella Rodman Church. Illustrated. 

IV. 
HOME GROUNDS. By A. F. Oaket. Illustrated. 

V. 

HOME DECORATION. Instructions iu and Designs for Embroidery, Panel 
and Decorative Paintings, Wood -carving, etc. By Janet E. Ruutz-Rees, 
author of M Horace Vernet." Illustrated. 

VI 

THE HOME NEEDLE. By Ella Rodman Church. Illustrated. 

VII. 
AMENITIES OF HOME. By M. E. W. S. 

VIII. 

HOUSEHOLD HINTS. A Book of Home Receipts and Home Suggestions. 
By Mm. Emma W. Babcock. 

IX. 

THE HOME LIBRARY. By Arthur Penn, editor of "The Rhymester.'' 
Illustrated. 

X. 

HOME QCQI^fATIONS. By Janet E. Ruutz-Rees. Hlustrated. 

y9l4 

HOME AMUSEMENTS. By M. E. W. S., author of "Amenities of Home," 

% (\) 



ALTH AT HOME. By A. H. Guernsey, and I. P. Davis, M. D., au- 
thor of 4k Hygiene for Girls." 

The London *' Saturday Review" commends "The Home Library" (in 
Appletons' Home Books") as a "practical, sngsestive, serviceable volume, 
belonging to a series of what may be called domestic guide-books, all useful, 
instructive, and convenient in their way; none of them commanding the full 
agreement of English readers, but most of them, like the present volume, emanat- 
ing from persons of much wider knowledge and experience than the generality 
of Householders, and therefore likely to gnlde them aright where their ov, r n taste 
or sheer accident might lead them wrong." 



New York: D. APPLETON & CO., 1, 3, & 5 Bond Street. 












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